diff --git a/crates/caldav/src/calendar/methods/mkcalendar.rs b/crates/caldav/src/calendar/methods/mkcalendar.rs
index 32f942b..ab36b08 100644
--- a/crates/caldav/src/calendar/methods/mkcalendar.rs
+++ b/crates/caldav/src/calendar/methods/mkcalendar.rs
@@ -5,7 +5,6 @@ use rustical_store::auth::User;
 use rustical_store::model::Calendar;
 use rustical_store::CalendarStore;
 use serde::{Deserialize, Serialize};
-use tokio::sync::RwLock;
 
 #[derive(Deserialize, Serialize, Clone, Debug)]
 #[serde(rename_all = "kebab-case")]
@@ -57,7 +56,7 @@ pub async fn route_mkcalendar<C: CalendarStore + ?Sized>(
     path: Path<(String, String)>,
     body: String,
     user: User,
-    store: Data<RwLock<C>>,
+    store: Data<C>,
 ) -> Result<HttpResponse, Error> {
     let (principal, cal_id) = path.into_inner();
     if principal != user.id {
@@ -79,7 +78,7 @@ pub async fn route_mkcalendar<C: CalendarStore + ?Sized>(
         synctoken: 0,
     };
 
-    match store.read().await.get_calendar(&principal, &cal_id).await {
+    match store.get_calendar(&principal, &cal_id).await {
         Err(rustical_store::Error::NotFound) => {
             // No conflict, no worries
         }
@@ -93,7 +92,7 @@ pub async fn route_mkcalendar<C: CalendarStore + ?Sized>(
         }
     }
 
-    match store.write().await.insert_calendar(calendar).await {
+    match store.insert_calendar(calendar).await {
         // The spec says we should return a mkcalendar-response but I don't know what goes into it.
         // However, it works without one but breaks on iPadOS when using an empty one :)
         Ok(()) => Ok(HttpResponse::Created()
diff --git a/crates/caldav/src/calendar/methods/report/calendar_multiget.rs b/crates/caldav/src/calendar/methods/report/calendar_multiget.rs
index df8ff75..efa4be3 100644
--- a/crates/caldav/src/calendar/methods/report/calendar_multiget.rs
+++ b/crates/caldav/src/calendar/methods/report/calendar_multiget.rs
@@ -18,7 +18,6 @@ use rustical_dav::{
 };
 use rustical_store::{model::object::CalendarObject, CalendarStore};
 use serde::Deserialize;
-use tokio::sync::RwLock;
 
 #[derive(Deserialize, Clone, Debug)]
 #[serde(rename_all = "kebab-case")]
@@ -35,7 +34,7 @@ pub async fn get_objects_calendar_multiget<C: CalendarStore + ?Sized>(
     principal_url: &str,
     principal: &str,
     cal_id: &str,
-    store: &RwLock<C>,
+    store: &C,
 ) -> Result<(Vec<CalendarObject>, Vec<String>), Error> {
     let resource_def =
         ResourceDef::prefix(principal_url).join(&ResourceDef::new("/{cal_id}/{object_id}"));
@@ -43,7 +42,6 @@ pub async fn get_objects_calendar_multiget<C: CalendarStore + ?Sized>(
     let mut result = vec![];
     let mut not_found = vec![];
 
-    let store = store.read().await;
     for href in &cal_query.href {
         let mut path = Path::new(href.as_str());
         if !resource_def.capture_match_info(&mut path) {
@@ -69,7 +67,7 @@ pub async fn handle_calendar_multiget<C: CalendarStore + ?Sized>(
     req: HttpRequest,
     principal: &str,
     cal_id: &str,
-    cal_store: &RwLock<C>,
+    cal_store: &C,
 ) -> Result<MultistatusElement<PropstatWrapper<CalendarObjectProp>, String>, Error> {
     let principal_url = PrincipalResource::get_url(req.resource_map(), vec![principal]).unwrap();
     let (objects, not_found) =
diff --git a/crates/caldav/src/calendar/methods/report/calendar_query.rs b/crates/caldav/src/calendar/methods/report/calendar_query.rs
index 2ed5e84..9fbb915 100644
--- a/crates/caldav/src/calendar/methods/report/calendar_query.rs
+++ b/crates/caldav/src/calendar/methods/report/calendar_query.rs
@@ -7,7 +7,6 @@ use rustical_dav::{
 };
 use rustical_store::{model::object::CalendarObject, CalendarStore};
 use serde::Deserialize;
-use tokio::sync::RwLock;
 
 use crate::{
     calendar_object::resource::{CalendarObjectProp, CalendarObjectResource},
@@ -195,9 +194,9 @@ pub async fn get_objects_calendar_query<C: CalendarStore + ?Sized>(
     cal_query: &CalendarQueryRequest,
     principal: &str,
     cal_id: &str,
-    store: &RwLock<C>,
+    store: &C,
 ) -> Result<Vec<CalendarObject>, Error> {
-    let mut objects = store.read().await.get_objects(principal, cal_id).await?;
+    let mut objects = store.get_objects(principal, cal_id).await?;
     if let Some(filter) = &cal_query.filter {
         objects.retain(|object| filter.matches(object));
     }
@@ -209,7 +208,7 @@ pub async fn handle_calendar_query<C: CalendarStore + ?Sized>(
     req: HttpRequest,
     principal: &str,
     cal_id: &str,
-    cal_store: &RwLock<C>,
+    cal_store: &C,
 ) -> Result<MultistatusElement<PropstatWrapper<CalendarObjectProp>, String>, Error> {
     let objects = get_objects_calendar_query(&cal_query, principal, cal_id, cal_store).await?;
 
diff --git a/crates/caldav/src/calendar/methods/report/mod.rs b/crates/caldav/src/calendar/methods/report/mod.rs
index b652d51..c54ccb5 100644
--- a/crates/caldav/src/calendar/methods/report/mod.rs
+++ b/crates/caldav/src/calendar/methods/report/mod.rs
@@ -8,7 +8,6 @@ use calendar_query::{handle_calendar_query, CalendarQueryRequest};
 use rustical_store::{auth::User, CalendarStore};
 use serde::{Deserialize, Serialize};
 use sync_collection::{handle_sync_collection, SyncCollectionRequest};
-use tokio::sync::RwLock;
 use tracing::instrument;
 
 mod calendar_multiget;
@@ -37,7 +36,7 @@ pub async fn route_report_calendar<C: CalendarStore + ?Sized>(
     body: String,
     user: User,
     req: HttpRequest,
-    cal_store: Data<RwLock<C>>,
+    cal_store: Data<C>,
 ) -> Result<impl Responder, Error> {
     let (principal, cal_id) = path.into_inner();
     if principal != user.id {
@@ -48,13 +47,21 @@ pub async fn route_report_calendar<C: CalendarStore + ?Sized>(
 
     Ok(match request.clone() {
         ReportRequest::CalendarQuery(cal_query) => {
-            handle_calendar_query(cal_query, req, &principal, &cal_id, &cal_store).await?
+            handle_calendar_query(cal_query, req, &principal, &cal_id, cal_store.as_ref()).await?
         }
         ReportRequest::CalendarMultiget(cal_multiget) => {
-            handle_calendar_multiget(cal_multiget, req, &principal, &cal_id, &cal_store).await?
+            handle_calendar_multiget(cal_multiget, req, &principal, &cal_id, cal_store.as_ref())
+                .await?
         }
         ReportRequest::SyncCollection(sync_collection) => {
-            handle_sync_collection(sync_collection, req, &principal, &cal_id, &cal_store).await?
+            handle_sync_collection(
+                sync_collection,
+                req,
+                &principal,
+                &cal_id,
+                cal_store.as_ref(),
+            )
+            .await?
         }
     })
 }
diff --git a/crates/caldav/src/calendar/methods/report/sync_collection.rs b/crates/caldav/src/calendar/methods/report/sync_collection.rs
index 201c8e7..7d40c02 100644
--- a/crates/caldav/src/calendar/methods/report/sync_collection.rs
+++ b/crates/caldav/src/calendar/methods/report/sync_collection.rs
@@ -12,7 +12,6 @@ use rustical_store::{
     CalendarStore,
 };
 use serde::Deserialize;
-use tokio::sync::RwLock;
 
 use crate::{
     calendar_object::resource::{CalendarObjectProp, CalendarObjectResource},
@@ -47,7 +46,7 @@ pub async fn handle_sync_collection<C: CalendarStore + ?Sized>(
     req: HttpRequest,
     principal: &str,
     cal_id: &str,
-    cal_store: &RwLock<C>,
+    cal_store: &C,
 ) -> Result<MultistatusElement<PropstatWrapper<CalendarObjectProp>, String>, Error> {
     let props = match sync_collection.prop {
         PropfindType::Allprop => {
@@ -62,8 +61,6 @@ pub async fn handle_sync_collection<C: CalendarStore + ?Sized>(
 
     let old_synctoken = parse_synctoken(&sync_collection.sync_token).unwrap_or(0);
     let (new_objects, deleted_objects, new_synctoken) = cal_store
-        .read()
-        .await
         .sync_changes(principal, cal_id, old_synctoken)
         .await?;
 
diff --git a/crates/caldav/src/calendar/resource.rs b/crates/caldav/src/calendar/resource.rs
index f5e7a7e..0975bb3 100644
--- a/crates/caldav/src/calendar/resource.rs
+++ b/crates/caldav/src/calendar/resource.rs
@@ -21,10 +21,9 @@ use serde::{Deserialize, Serialize};
 use std::str::FromStr;
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
 
 pub struct CalendarResourceService<C: CalendarStore + ?Sized> {
-    pub cal_store: Arc<RwLock<C>>,
+    pub cal_store: Arc<C>,
     pub path: String,
     pub principal: String,
     pub calendar_id: String,
@@ -261,8 +260,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarResourceService<C> {
         }
         let calendar = self
             .cal_store
-            .read()
-            .await
             .get_calendar(&self.principal, &self.calendar_id)
             .await
             .map_err(|_e| Error::NotFound)?;
@@ -275,8 +272,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarResourceService<C> {
     ) -> Result<Vec<(String, Self::MemberType)>, Self::Error> {
         Ok(self
             .cal_store
-            .read()
-            .await
             .get_objects(&self.principal, &self.calendar_id)
             .await?
             .into_iter()
@@ -298,7 +293,7 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarResourceService<C> {
         path_components: Self::PathComponents,
     ) -> Result<Self, Self::Error> {
         let cal_store = req
-            .app_data::<Data<RwLock<C>>>()
+            .app_data::<Data<C>>()
             .expect("no calendar store in app_data!")
             .clone()
             .into_inner();
@@ -313,8 +308,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarResourceService<C> {
 
     async fn save_resource(&self, file: Self::Resource) -> Result<(), Self::Error> {
         self.cal_store
-            .write()
-            .await
             .update_calendar(
                 self.principal.to_owned(),
                 self.calendar_id.to_owned(),
@@ -326,8 +319,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarResourceService<C> {
 
     async fn delete_resource(&self, use_trashbin: bool) -> Result<(), Self::Error> {
         self.cal_store
-            .write()
-            .await
             .delete_calendar(&self.principal, &self.calendar_id, use_trashbin)
             .await?;
         Ok(())
diff --git a/crates/caldav/src/calendar_object/methods.rs b/crates/caldav/src/calendar_object/methods.rs
index 40f4cf7..8b6d4da 100644
--- a/crates/caldav/src/calendar_object/methods.rs
+++ b/crates/caldav/src/calendar_object/methods.rs
@@ -7,7 +7,6 @@ use actix_web::HttpResponse;
 use rustical_store::auth::User;
 use rustical_store::model::CalendarObject;
 use rustical_store::CalendarStore;
-use tokio::sync::RwLock;
 use tracing::instrument;
 use tracing_actix_web::RootSpan;
 
@@ -16,7 +15,7 @@ use super::resource::CalendarObjectPathComponents;
 #[instrument(parent = root_span.id(), skip(store, root_span))]
 pub async fn get_event<C: CalendarStore + ?Sized>(
     path: Path<CalendarObjectPathComponents>,
-    store: Data<RwLock<C>>,
+    store: Data<C>,
     user: User,
     root_span: RootSpan,
 ) -> Result<HttpResponse, Error> {
@@ -30,16 +29,12 @@ pub async fn get_event<C: CalendarStore + ?Sized>(
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let calendar = store.read().await.get_calendar(&principal, &cal_id).await?;
+    let calendar = store.get_calendar(&principal, &cal_id).await?;
     if user.id != calendar.principal {
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let event = store
-        .read()
-        .await
-        .get_object(&principal, &cal_id, &object_id)
-        .await?;
+    let event = store.get_object(&principal, &cal_id, &object_id).await?;
 
     Ok(HttpResponse::Ok()
         .insert_header(("ETag", event.get_etag()))
@@ -50,7 +45,7 @@ pub async fn get_event<C: CalendarStore + ?Sized>(
 #[instrument(parent = root_span.id(), skip(store, req, root_span))]
 pub async fn put_event<C: CalendarStore + ?Sized>(
     path: Path<CalendarObjectPathComponents>,
-    store: Data<RwLock<C>>,
+    store: Data<C>,
     body: String,
     user: User,
     req: HttpRequest,
@@ -66,37 +61,16 @@ pub async fn put_event<C: CalendarStore + ?Sized>(
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let calendar = store.read().await.get_calendar(&principal, &cal_id).await?;
-    if user.id != calendar.principal {
-        return Ok(HttpResponse::Unauthorized().body(""));
-    }
-
     // TODO: implement If-Match
     //
-    let mut store_write = store.write().await;
 
-    if Some(&HeaderValue::from_static("*")) == req.headers().get(header::IF_NONE_MATCH) {
-        // Only write if not existing
-        match store_write
-            .get_object(&principal, &cal_id, &object_id)
-            .await
-        {
-            Ok(_) => {
-                // Conflict
-                return Ok(HttpResponse::Conflict().body("Resource with this URI already exists"));
-            }
-            Err(rustical_store::Error::NotFound) => {
-                // Path unused, we can proceed
-            }
-            Err(err) => {
-                // Some unknown error :(
-                return Err(err.into());
-            }
-        }
-    }
+    let overwrite =
+        Some(&HeaderValue::from_static("*")) != req.headers().get(header::IF_NONE_MATCH);
 
     let object = CalendarObject::from_ics(object_id, body)?;
-    store_write.put_object(principal, cal_id, object).await?;
+    store
+        .put_object(principal, cal_id, object, overwrite)
+        .await?;
 
     Ok(HttpResponse::Created().body(""))
 }
diff --git a/crates/caldav/src/calendar_object/resource.rs b/crates/caldav/src/calendar_object/resource.rs
index 9477745..715c002 100644
--- a/crates/caldav/src/calendar_object/resource.rs
+++ b/crates/caldav/src/calendar_object/resource.rs
@@ -1,3 +1,4 @@
+use super::methods::{get_event, put_event};
 use crate::Error;
 use actix_web::{dev::ResourceMap, web::Data, HttpRequest};
 use async_trait::async_trait;
@@ -8,12 +9,9 @@ use rustical_store::CalendarStore;
 use serde::{Deserialize, Serialize};
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
-
-use super::methods::{get_event, put_event};
 
 pub struct CalendarObjectResourceService<C: CalendarStore + ?Sized> {
-    pub cal_store: Arc<RwLock<C>>,
+    pub cal_store: Arc<C>,
     pub path: String,
     pub principal: String,
     pub cal_id: String,
@@ -121,7 +119,7 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarObjectResourceServic
         } = path_components;
 
         let cal_store = req
-            .app_data::<Data<RwLock<C>>>()
+            .app_data::<Data<C>>()
             .expect("no calendar store in app_data!")
             .clone()
             .into_inner();
@@ -141,8 +139,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarObjectResourceServic
         }
         let event = self
             .cal_store
-            .read()
-            .await
             .get_object(&self.principal, &self.cal_id, &self.object_id)
             .await?;
         Ok(event.into())
@@ -154,8 +150,6 @@ impl<C: CalendarStore + ?Sized> ResourceService for CalendarObjectResourceServic
 
     async fn delete_resource(&self, use_trashbin: bool) -> Result<(), Self::Error> {
         self.cal_store
-            .write()
-            .await
             .delete_object(&self.principal, &self.cal_id, &self.object_id, use_trashbin)
             .await?;
         Ok(())
diff --git a/crates/caldav/src/error.rs b/crates/caldav/src/error.rs
index 5edb3de..270684f 100644
--- a/crates/caldav/src/error.rs
+++ b/crates/caldav/src/error.rs
@@ -29,7 +29,7 @@ impl actix_web::ResponseError for Error {
         match self {
             Error::StoreError(err) => match err {
                 rustical_store::Error::NotFound => StatusCode::NOT_FOUND,
-                rustical_store::Error::InvalidIcs(_) => StatusCode::BAD_REQUEST,
+                rustical_store::Error::InvalidData(_) => StatusCode::BAD_REQUEST,
                 _ => StatusCode::INTERNAL_SERVER_ERROR,
             },
             Error::DavError(err) => err.status_code(),
diff --git a/crates/caldav/src/lib.rs b/crates/caldav/src/lib.rs
index 540443f..93aa7ea 100644
--- a/crates/caldav/src/lib.rs
+++ b/crates/caldav/src/lib.rs
@@ -11,7 +11,6 @@ use rustical_dav::resource::ResourceService;
 use rustical_store::auth::{AuthenticationMiddleware, AuthenticationProvider};
 use rustical_store::CalendarStore;
 use std::sync::Arc;
-use tokio::sync::RwLock;
 
 pub mod calendar;
 pub mod calendar_object;
@@ -28,7 +27,7 @@ pub fn configure_well_known(cfg: &mut web::ServiceConfig, caldav_root: String) {
 pub fn configure_dav<AP: AuthenticationProvider, C: CalendarStore + ?Sized>(
     cfg: &mut web::ServiceConfig,
     auth_provider: Arc<AP>,
-    store: Arc<RwLock<C>>,
+    store: Arc<C>,
 ) {
     cfg.service(
         web::scope("")
diff --git a/crates/caldav/src/principal/mod.rs b/crates/caldav/src/principal/mod.rs
index a35b19c..80c5737 100644
--- a/crates/caldav/src/principal/mod.rs
+++ b/crates/caldav/src/principal/mod.rs
@@ -1,3 +1,4 @@
+use crate::calendar::resource::CalendarResource;
 use crate::Error;
 use actix_web::dev::ResourceMap;
 use actix_web::web::Data;
@@ -9,13 +10,10 @@ use rustical_store::CalendarStore;
 use serde::{Deserialize, Serialize};
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
-
-use crate::calendar::resource::CalendarResource;
 
 pub struct PrincipalResourceService<C: CalendarStore + ?Sized> {
     principal: String,
-    cal_store: Arc<RwLock<C>>,
+    cal_store: Arc<C>,
 }
 
 #[derive(Clone)]
@@ -113,7 +111,7 @@ impl<C: CalendarStore + ?Sized> ResourceService for PrincipalResourceService<C>
         (principal,): Self::PathComponents,
     ) -> Result<Self, Self::Error> {
         let cal_store = req
-            .app_data::<Data<RwLock<C>>>()
+            .app_data::<Data<C>>()
             .expect("no calendar store in app_data!")
             .clone()
             .into_inner();
@@ -137,12 +135,7 @@ impl<C: CalendarStore + ?Sized> ResourceService for PrincipalResourceService<C>
         &self,
         rmap: &ResourceMap,
     ) -> Result<Vec<(String, Self::MemberType)>, Self::Error> {
-        let calendars = self
-            .cal_store
-            .read()
-            .await
-            .get_calendars(&self.principal)
-            .await?;
+        let calendars = self.cal_store.get_calendars(&self.principal).await?;
         Ok(calendars
             .into_iter()
             .map(|cal| {
diff --git a/crates/carddav/src/address_object/methods.rs b/crates/carddav/src/address_object/methods.rs
index 25a40ee..91b061f 100644
--- a/crates/carddav/src/address_object/methods.rs
+++ b/crates/carddav/src/address_object/methods.rs
@@ -8,14 +8,13 @@ use actix_web::HttpResponse;
 use rustical_store::auth::User;
 use rustical_store::model::AddressObject;
 use rustical_store::AddressbookStore;
-use tokio::sync::RwLock;
 use tracing::instrument;
 use tracing_actix_web::RootSpan;
 
 #[instrument(parent = root_span.id(), skip(store, root_span))]
 pub async fn get_object<AS: AddressbookStore + ?Sized>(
     path: Path<AddressObjectPathComponents>,
-    store: Data<RwLock<AS>>,
+    store: Data<AS>,
     user: User,
     root_span: RootSpan,
 ) -> Result<HttpResponse, Error> {
@@ -29,20 +28,12 @@ pub async fn get_object<AS: AddressbookStore + ?Sized>(
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let addressbook = store
-        .read()
-        .await
-        .get_addressbook(&principal, &cal_id)
-        .await?;
+    let addressbook = store.get_addressbook(&principal, &cal_id).await?;
     if user.id != addressbook.principal {
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let object = store
-        .read()
-        .await
-        .get_object(&principal, &cal_id, &object_id)
-        .await?;
+    let object = store.get_object(&principal, &cal_id, &object_id).await?;
 
     Ok(HttpResponse::Ok()
         .insert_header(("ETag", object.get_etag()))
@@ -53,7 +44,7 @@ pub async fn get_object<AS: AddressbookStore + ?Sized>(
 #[instrument(parent = root_span.id(), skip(store, req, root_span))]
 pub async fn put_object<AS: AddressbookStore + ?Sized>(
     path: Path<AddressObjectPathComponents>,
-    store: Data<RwLock<AS>>,
+    store: Data<AS>,
     body: String,
     user: User,
     req: HttpRequest,
@@ -69,42 +60,15 @@ pub async fn put_object<AS: AddressbookStore + ?Sized>(
         return Ok(HttpResponse::Unauthorized().body(""));
     }
 
-    let addressbook = store
-        .read()
-        .await
-        .get_addressbook(&principal, &addressbook_id)
-        .await?;
-    if user.id != addressbook.principal {
-        return Ok(HttpResponse::Unauthorized().body(""));
-    }
-
     // TODO: implement If-Match
     //
-    let mut store_write = store.write().await;
 
-    if Some(&HeaderValue::from_static("*")) == req.headers().get(header::IF_NONE_MATCH) {
-        // Only write if not existing
-        match store_write
-            .get_object(&principal, &addressbook_id, &object_id)
-            .await
-        {
-            Ok(_) => {
-                // Conflict
-                return Ok(HttpResponse::Conflict().body("Resource with this URI already exists"));
-            }
-            Err(rustical_store::Error::NotFound) => {
-                // Path unused, we can proceed
-            }
-            Err(err) => {
-                // Some unknown error :(
-                return Err(err.into());
-            }
-        }
-    }
+    let overwrite =
+        Some(&HeaderValue::from_static("*")) != req.headers().get(header::IF_NONE_MATCH);
 
     let object = AddressObject::from_vcf(object_id, body)?;
-    store_write
-        .put_object(principal, addressbook_id, object)
+    store
+        .put_object(principal, addressbook_id, object, overwrite)
         .await?;
 
     Ok(HttpResponse::Created().body(""))
diff --git a/crates/carddav/src/address_object/resource.rs b/crates/carddav/src/address_object/resource.rs
index 7f10749..9426449 100644
--- a/crates/carddav/src/address_object/resource.rs
+++ b/crates/carddav/src/address_object/resource.rs
@@ -7,12 +7,11 @@ use rustical_store::{model::AddressObject, AddressbookStore};
 use serde::{Deserialize, Serialize};
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
 
 use super::methods::{get_object, put_object};
 
 pub struct AddressObjectResourceService<AS: AddressbookStore + ?Sized> {
-    pub addr_store: Arc<RwLock<AS>>,
+    pub addr_store: Arc<AS>,
     pub path: String,
     pub principal: String,
     pub cal_id: String,
@@ -120,7 +119,7 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressObjectResourceSer
         } = path_components;
 
         let addr_store = req
-            .app_data::<Data<RwLock<AS>>>()
+            .app_data::<Data<AS>>()
             .expect("no addressbook store in app_data!")
             .clone()
             .into_inner();
@@ -140,8 +139,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressObjectResourceSer
         }
         let event = self
             .addr_store
-            .read()
-            .await
             .get_object(&self.principal, &self.cal_id, &self.object_id)
             .await?;
         Ok(event.into())
@@ -153,8 +150,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressObjectResourceSer
 
     async fn delete_resource(&self, use_trashbin: bool) -> Result<(), Self::Error> {
         self.addr_store
-            .write()
-            .await
             .delete_object(&self.principal, &self.cal_id, &self.object_id, use_trashbin)
             .await?;
         Ok(())
diff --git a/crates/carddav/src/addressbook/methods/mkcol.rs b/crates/carddav/src/addressbook/methods/mkcol.rs
index 47c6806..ce04e36 100644
--- a/crates/carddav/src/addressbook/methods/mkcol.rs
+++ b/crates/carddav/src/addressbook/methods/mkcol.rs
@@ -4,7 +4,6 @@ use actix_web::{web::Data, HttpResponse};
 use rustical_store::model::Addressbook;
 use rustical_store::{auth::User, AddressbookStore};
 use serde::{Deserialize, Serialize};
-use tokio::sync::RwLock;
 
 #[derive(Deserialize, Serialize, Clone, Debug)]
 #[serde(rename_all = "kebab-case")]
@@ -38,7 +37,7 @@ pub async fn route_mkcol<AS: AddressbookStore + ?Sized>(
     path: Path<(String, String)>,
     body: String,
     user: User,
-    store: Data<RwLock<AS>>,
+    store: Data<AS>,
 ) -> Result<HttpResponse, Error> {
     let (principal, addressbook_id) = path.into_inner();
     if principal != user.id {
@@ -57,12 +56,7 @@ pub async fn route_mkcol<AS: AddressbookStore + ?Sized>(
         synctoken: 0,
     };
 
-    match store
-        .read()
-        .await
-        .get_addressbook(&principal, &addressbook_id)
-        .await
-    {
+    match store.get_addressbook(&principal, &addressbook_id).await {
         Err(rustical_store::Error::NotFound) => {
             // No conflict, no worries
         }
@@ -76,7 +70,7 @@ pub async fn route_mkcol<AS: AddressbookStore + ?Sized>(
         }
     }
 
-    match store.write().await.insert_addressbook(addressbook).await {
+    match store.insert_addressbook(addressbook).await {
         // TODO: The spec says we should return a mkcol-response.
         // However, it works without one but breaks on iPadOS when using an empty one :)
         Ok(()) => Ok(HttpResponse::Created()
diff --git a/crates/carddav/src/addressbook/methods/report/addressbook_multiget.rs b/crates/carddav/src/addressbook/methods/report/addressbook_multiget.rs
index b4c2f25..a361b5e 100644
--- a/crates/carddav/src/addressbook/methods/report/addressbook_multiget.rs
+++ b/crates/carddav/src/addressbook/methods/report/addressbook_multiget.rs
@@ -18,7 +18,6 @@ use rustical_dav::{
 };
 use rustical_store::{model::AddressObject, AddressbookStore};
 use serde::Deserialize;
-use tokio::sync::RwLock;
 
 #[derive(Deserialize, Clone, Debug)]
 #[serde(rename_all = "kebab-case")]
@@ -34,7 +33,7 @@ pub async fn get_objects_addressbook_multiget<AS: AddressbookStore + ?Sized>(
     principal_url: &str,
     principal: &str,
     addressbook_id: &str,
-    store: &RwLock<AS>,
+    store: &AS,
 ) -> Result<(Vec<AddressObject>, Vec<String>), Error> {
     let resource_def =
         ResourceDef::prefix(principal_url).join(&ResourceDef::new("/{addressbook_id}/{object_id}"));
@@ -42,7 +41,6 @@ pub async fn get_objects_addressbook_multiget<AS: AddressbookStore + ?Sized>(
     let mut result = vec![];
     let mut not_found = vec![];
 
-    let store = store.read().await;
     for href in &addressbook_multiget.href {
         let mut path = Path::new(href.as_str());
         if !resource_def.capture_match_info(&mut path) {
@@ -68,7 +66,7 @@ pub async fn handle_addressbook_multiget<AS: AddressbookStore + ?Sized>(
     req: HttpRequest,
     principal: &str,
     cal_id: &str,
-    addr_store: &RwLock<AS>,
+    addr_store: &AS,
 ) -> Result<MultistatusElement<PropstatWrapper<AddressObjectProp>, String>, Error> {
     let principal_url = PrincipalResource::get_url(req.resource_map(), vec![principal]).unwrap();
     let (objects, not_found) = get_objects_addressbook_multiget(
diff --git a/crates/carddav/src/addressbook/methods/report/mod.rs b/crates/carddav/src/addressbook/methods/report/mod.rs
index d3b13da..34b21ec 100644
--- a/crates/carddav/src/addressbook/methods/report/mod.rs
+++ b/crates/carddav/src/addressbook/methods/report/mod.rs
@@ -7,7 +7,6 @@ use addressbook_multiget::{handle_addressbook_multiget, AddressbookMultigetReque
 use rustical_store::{auth::User, AddressbookStore};
 use serde::{Deserialize, Serialize};
 use sync_collection::{handle_sync_collection, SyncCollectionRequest};
-use tokio::sync::RwLock;
 use tracing::instrument;
 
 mod addressbook_multiget;
@@ -34,7 +33,7 @@ pub async fn route_report_addressbook<AS: AddressbookStore + ?Sized>(
     body: String,
     user: User,
     req: HttpRequest,
-    addr_store: Data<RwLock<AS>>,
+    addr_store: Data<AS>,
 ) -> Result<impl Responder, Error> {
     let (principal, addressbook_id) = path.into_inner();
     if principal != user.id {
@@ -50,7 +49,7 @@ pub async fn route_report_addressbook<AS: AddressbookStore + ?Sized>(
                 req,
                 &principal,
                 &addressbook_id,
-                &addr_store,
+                addr_store.as_ref(),
             )
             .await?
         }
@@ -60,7 +59,7 @@ pub async fn route_report_addressbook<AS: AddressbookStore + ?Sized>(
                 req,
                 &principal,
                 &addressbook_id,
-                &addr_store,
+                addr_store.as_ref(),
             )
             .await?
         }
diff --git a/crates/carddav/src/addressbook/methods/report/sync_collection.rs b/crates/carddav/src/addressbook/methods/report/sync_collection.rs
index 0487c49..b5bb8b8 100644
--- a/crates/carddav/src/addressbook/methods/report/sync_collection.rs
+++ b/crates/carddav/src/addressbook/methods/report/sync_collection.rs
@@ -16,7 +16,6 @@ use rustical_store::{
     AddressbookStore,
 };
 use serde::Deserialize;
-use tokio::sync::RwLock;
 
 #[derive(Deserialize, Clone, Debug)]
 #[serde(rename_all = "kebab-case")]
@@ -45,7 +44,7 @@ pub async fn handle_sync_collection<AS: AddressbookStore + ?Sized>(
     req: HttpRequest,
     principal: &str,
     addressbook_id: &str,
-    addr_store: &RwLock<AS>,
+    addr_store: &AS,
 ) -> Result<MultistatusElement<PropstatWrapper<AddressObjectProp>, String>, Error> {
     let props = match sync_collection.prop {
         PropfindType::Allprop => {
@@ -60,8 +59,6 @@ pub async fn handle_sync_collection<AS: AddressbookStore + ?Sized>(
 
     let old_synctoken = parse_synctoken(&sync_collection.sync_token).unwrap_or(0);
     let (new_objects, deleted_objects, new_synctoken) = addr_store
-        .read()
-        .await
         .sync_changes(principal, addressbook_id, old_synctoken)
         .await?;
 
diff --git a/crates/carddav/src/addressbook/resource.rs b/crates/carddav/src/addressbook/resource.rs
index f1443d2..a9673f9 100644
--- a/crates/carddav/src/addressbook/resource.rs
+++ b/crates/carddav/src/addressbook/resource.rs
@@ -18,10 +18,9 @@ use serde::{Deserialize, Serialize};
 use std::str::FromStr;
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
 
 pub struct AddressbookResourceService<AS: AddressbookStore + ?Sized> {
-    pub addr_store: Arc<RwLock<AS>>,
+    pub addr_store: Arc<AS>,
     pub path: String,
     pub principal: String,
     pub addressbook_id: String,
@@ -204,8 +203,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressbookResourceServi
         }
         let addressbook = self
             .addr_store
-            .read()
-            .await
             .get_addressbook(&self.principal, &self.addressbook_id)
             .await
             .map_err(|_e| Error::NotFound)?;
@@ -218,8 +215,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressbookResourceServi
     ) -> Result<Vec<(String, Self::MemberType)>, Self::Error> {
         Ok(self
             .addr_store
-            .read()
-            .await
             .get_objects(&self.principal, &self.addressbook_id)
             .await?
             .into_iter()
@@ -241,7 +236,7 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressbookResourceServi
         path_components: Self::PathComponents,
     ) -> Result<Self, Self::Error> {
         let addr_store = req
-            .app_data::<Data<RwLock<AS>>>()
+            .app_data::<Data<AS>>()
             .expect("no addressbook store in app_data!")
             .clone()
             .into_inner();
@@ -256,8 +251,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressbookResourceServi
 
     async fn save_resource(&self, file: Self::Resource) -> Result<(), Self::Error> {
         self.addr_store
-            .write()
-            .await
             .update_addressbook(
                 self.principal.to_owned(),
                 self.addressbook_id.to_owned(),
@@ -269,8 +262,6 @@ impl<AS: AddressbookStore + ?Sized> ResourceService for AddressbookResourceServi
 
     async fn delete_resource(&self, use_trashbin: bool) -> Result<(), Self::Error> {
         self.addr_store
-            .write()
-            .await
             .delete_addressbook(&self.principal, &self.addressbook_id, use_trashbin)
             .await?;
         Ok(())
diff --git a/crates/carddav/src/error.rs b/crates/carddav/src/error.rs
index 5edb3de..270684f 100644
--- a/crates/carddav/src/error.rs
+++ b/crates/carddav/src/error.rs
@@ -29,7 +29,7 @@ impl actix_web::ResponseError for Error {
         match self {
             Error::StoreError(err) => match err {
                 rustical_store::Error::NotFound => StatusCode::NOT_FOUND,
-                rustical_store::Error::InvalidIcs(_) => StatusCode::BAD_REQUEST,
+                rustical_store::Error::InvalidData(_) => StatusCode::BAD_REQUEST,
                 _ => StatusCode::INTERNAL_SERVER_ERROR,
             },
             Error::DavError(err) => err.status_code(),
diff --git a/crates/carddav/src/lib.rs b/crates/carddav/src/lib.rs
index 3e4104a..bc750bd 100644
--- a/crates/carddav/src/lib.rs
+++ b/crates/carddav/src/lib.rs
@@ -18,7 +18,6 @@ use rustical_store::{
     AddressbookStore,
 };
 use std::sync::Arc;
-use tokio::sync::RwLock;
 
 pub mod address_object;
 pub mod addressbook;
@@ -33,7 +32,7 @@ pub fn configure_well_known(cfg: &mut web::ServiceConfig, carddav_root: String)
 pub fn configure_dav<AP: AuthenticationProvider, A: AddressbookStore + ?Sized>(
     cfg: &mut web::ServiceConfig,
     auth_provider: Arc<AP>,
-    store: Arc<RwLock<A>>,
+    store: Arc<A>,
 ) {
     cfg.service(
         web::scope("")
diff --git a/crates/carddav/src/principal/mod.rs b/crates/carddav/src/principal/mod.rs
index 5bbd323..42a9736 100644
--- a/crates/carddav/src/principal/mod.rs
+++ b/crates/carddav/src/principal/mod.rs
@@ -10,11 +10,10 @@ use rustical_store::AddressbookStore;
 use serde::{Deserialize, Serialize};
 use std::sync::Arc;
 use strum::{EnumString, VariantNames};
-use tokio::sync::RwLock;
 
 pub struct PrincipalResourceService<A: AddressbookStore + ?Sized> {
     principal: String,
-    addr_store: Arc<RwLock<A>>,
+    addr_store: Arc<A>,
 }
 
 #[derive(Clone)]
@@ -111,7 +110,7 @@ impl<A: AddressbookStore + ?Sized> ResourceService for PrincipalResourceService<
         (principal,): Self::PathComponents,
     ) -> Result<Self, Self::Error> {
         let addr_store = req
-            .app_data::<Data<RwLock<A>>>()
+            .app_data::<Data<A>>()
             .expect("no addressbook store in app_data!")
             .clone()
             .into_inner();
@@ -135,12 +134,7 @@ impl<A: AddressbookStore + ?Sized> ResourceService for PrincipalResourceService<
         &self,
         rmap: &ResourceMap,
     ) -> Result<Vec<(String, Self::MemberType)>, Self::Error> {
-        let addressbooks = self
-            .addr_store
-            .read()
-            .await
-            .get_addressbooks(&self.principal)
-            .await?;
+        let addressbooks = self.addr_store.get_addressbooks(&self.principal).await?;
         Ok(addressbooks
             .into_iter()
             .map(|addressbook| {
diff --git a/crates/frontend/src/lib.rs b/crates/frontend/src/lib.rs
index 14cf4e4..7fa01b0 100644
--- a/crates/frontend/src/lib.rs
+++ b/crates/frontend/src/lib.rs
@@ -13,7 +13,6 @@ use rustical_store::{
     CalendarStore,
 };
 use std::sync::Arc;
-use tokio::sync::RwLock;
 
 mod config;
 mod routes;
@@ -29,10 +28,9 @@ struct UserPage {
 
 async fn route_user<C: CalendarStore + ?Sized>(
     path: Path<String>,
-    store: Data<RwLock<C>>,
+    store: Data<C>,
     user: User,
 ) -> impl Responder {
-    let store = store.read().await;
     let user_id = path.into_inner();
     UserPage {
         calendars: store.get_calendars(&user.id).await.unwrap(),
@@ -49,10 +47,9 @@ struct CalendarPage {
 
 async fn route_calendar<C: CalendarStore + ?Sized>(
     path: Path<(String, String)>,
-    store: Data<RwLock<C>>,
+    store: Data<C>,
     user: User,
 ) -> impl Responder {
-    let store = store.read().await;
     let (owner, cal_id) = path.into_inner();
     CalendarPage {
         owner: owner.to_owned(),
@@ -63,7 +60,7 @@ async fn route_calendar<C: CalendarStore + ?Sized>(
 pub fn configure_frontend<AP: AuthenticationProvider, C: CalendarStore + ?Sized>(
     cfg: &mut web::ServiceConfig,
     auth_provider: Arc<AP>,
-    store: Arc<RwLock<C>>,
+    store: Arc<C>,
 ) {
     cfg.service(
         web::scope("")
diff --git a/crates/store/src/addressbook_store.rs b/crates/store/src/addressbook_store.rs
index d0e7fa9..53a8eec 100644
--- a/crates/store/src/addressbook_store.rs
+++ b/crates/store/src/addressbook_store.rs
@@ -10,19 +10,19 @@ pub trait AddressbookStore: Send + Sync + 'static {
     async fn get_addressbooks(&self, principal: &str) -> Result<Vec<Addressbook>, Error>;
 
     async fn update_addressbook(
-        &mut self,
+        &self,
         principal: String,
         id: String,
         addressbook: Addressbook,
     ) -> Result<(), Error>;
-    async fn insert_addressbook(&mut self, addressbook: Addressbook) -> Result<(), Error>;
+    async fn insert_addressbook(&self, addressbook: Addressbook) -> Result<(), Error>;
     async fn delete_addressbook(
-        &mut self,
+        &self,
         principal: &str,
         name: &str,
         use_trashbin: bool,
     ) -> Result<(), Error>;
-    async fn restore_addressbook(&mut self, principal: &str, name: &str) -> Result<(), Error>;
+    async fn restore_addressbook(&self, principal: &str, name: &str) -> Result<(), Error>;
 
     async fn sync_changes(
         &self,
@@ -43,20 +43,21 @@ pub trait AddressbookStore: Send + Sync + 'static {
         object_id: &str,
     ) -> Result<AddressObject, Error>;
     async fn put_object(
-        &mut self,
+        &self,
         principal: String,
         addressbook_id: String,
         object: AddressObject,
+        overwrite: bool,
     ) -> Result<(), Error>;
     async fn delete_object(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
         object_id: &str,
         use_trashbin: bool,
     ) -> Result<(), Error>;
     async fn restore_object(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
         object_id: &str,
diff --git a/crates/store/src/calendar_store.rs b/crates/store/src/calendar_store.rs
index e7b5b5e..954906a 100644
--- a/crates/store/src/calendar_store.rs
+++ b/crates/store/src/calendar_store.rs
@@ -9,19 +9,19 @@ pub trait CalendarStore: Send + Sync + 'static {
     async fn get_calendars(&self, principal: &str) -> Result<Vec<Calendar>, Error>;
 
     async fn update_calendar(
-        &mut self,
+        &self,
         principal: String,
         id: String,
         calendar: Calendar,
     ) -> Result<(), Error>;
-    async fn insert_calendar(&mut self, calendar: Calendar) -> Result<(), Error>;
+    async fn insert_calendar(&self, calendar: Calendar) -> Result<(), Error>;
     async fn delete_calendar(
-        &mut self,
+        &self,
         principal: &str,
         name: &str,
         use_trashbin: bool,
     ) -> Result<(), Error>;
-    async fn restore_calendar(&mut self, principal: &str, name: &str) -> Result<(), Error>;
+    async fn restore_calendar(&self, principal: &str, name: &str) -> Result<(), Error>;
 
     async fn sync_changes(
         &self,
@@ -42,20 +42,21 @@ pub trait CalendarStore: Send + Sync + 'static {
         object_id: &str,
     ) -> Result<CalendarObject, Error>;
     async fn put_object(
-        &mut self,
+        &self,
         principal: String,
         cal_id: String,
         object: CalendarObject,
+        overwrite: bool,
     ) -> Result<(), Error>;
     async fn delete_object(
-        &mut self,
+        &self,
         principal: &str,
         cal_id: &str,
         object_id: &str,
         use_trashbin: bool,
     ) -> Result<(), Error>;
     async fn restore_object(
-        &mut self,
+        &self,
         principal: &str,
         cal_id: &str,
         object_id: &str,
diff --git a/crates/store/src/error.rs b/crates/store/src/error.rs
index eda4127..33d400f 100644
--- a/crates/store/src/error.rs
+++ b/crates/store/src/error.rs
@@ -3,8 +3,11 @@ pub enum Error {
     #[error("Not found")]
     NotFound,
 
-    #[error("Invalid ics input: {0}")]
-    InvalidIcs(String),
+    #[error("Resource already exists and overwrite=false")]
+    AlreadyExists,
+
+    #[error("Invalid ics/vcf input: {0}")]
+    InvalidData(String),
 
     #[error(transparent)]
     SqlxError(sqlx::Error),
diff --git a/crates/store/src/model/object.rs b/crates/store/src/model/object.rs
index ece295a..3ee3484 100644
--- a/crates/store/src/model/object.rs
+++ b/crates/store/src/model/object.rs
@@ -68,7 +68,7 @@ impl CalendarObject {
         let mut parser = ical::IcalParser::new(BufReader::new(ics.as_bytes()));
         let cal = parser.next().ok_or(Error::NotFound)??;
         if parser.next().is_some() {
-            return Err(Error::InvalidIcs(
+            return Err(Error::InvalidData(
                 "multiple calendars, only one allowed".to_owned(),
             ));
         }
@@ -80,7 +80,7 @@ impl CalendarObject {
             != 1
         {
             // https://datatracker.ietf.org/doc/html/rfc4791#section-4.1
-            return Err(Error::InvalidIcs(
+            return Err(Error::InvalidData(
                 "iCalendar object is only allowed to have exactly one component".to_owned(),
             ));
         }
@@ -114,7 +114,7 @@ impl CalendarObject {
             });
         }
 
-        Err(Error::InvalidIcs(
+        Err(Error::InvalidData(
             "iCalendar component type not supported :(".to_owned(),
         ))
     }
diff --git a/crates/store/src/sqlite_store/addressbook_store.rs b/crates/store/src/sqlite_store/addressbook_store.rs
index 927ccfd..16308df 100644
--- a/crates/store/src/sqlite_store/addressbook_store.rs
+++ b/crates/store/src/sqlite_store/addressbook_store.rs
@@ -99,7 +99,7 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn update_addressbook(
-        &mut self,
+        &self,
         principal: String,
         id: String,
         addressbook: Addressbook,
@@ -123,7 +123,7 @@ impl AddressbookStore for SqliteStore {
     }
 
     #[instrument]
-    async fn insert_addressbook(&mut self, addressbook: Addressbook) -> Result<(), Error> {
+    async fn insert_addressbook(&self, addressbook: Addressbook) -> Result<(), Error> {
         sqlx::query!(
             r#"INSERT INTO addressbooks (principal, id, displayname, description)
                 VALUES (?, ?, ?, ?)"#,
@@ -139,7 +139,7 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn delete_addressbook(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
         use_trashbin: bool,
@@ -168,7 +168,7 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn restore_addressbook(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
     ) -> Result<(), Error> {
@@ -264,10 +264,12 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn put_object(
-        &mut self,
+        &self,
         principal: String,
         addressbook_id: String,
         object: AddressObject,
+        // TODO: implement
+        overwrite: bool,
     ) -> Result<(), Error> {
         let mut tx = self.db.begin().await?;
 
@@ -298,7 +300,7 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn delete_object(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
         object_id: &str,
@@ -341,7 +343,7 @@ impl AddressbookStore for SqliteStore {
 
     #[instrument]
     async fn restore_object(
-        &mut self,
+        &self,
         principal: &str,
         addressbook_id: &str,
         object_id: &str,
diff --git a/crates/store/src/sqlite_store/calendar_store.rs b/crates/store/src/sqlite_store/calendar_store.rs
index 9031ef7..66a6bca 100644
--- a/crates/store/src/sqlite_store/calendar_store.rs
+++ b/crates/store/src/sqlite_store/calendar_store.rs
@@ -98,7 +98,7 @@ impl CalendarStore for SqliteStore {
     }
 
     #[instrument]
-    async fn insert_calendar(&mut self, calendar: Calendar) -> Result<(), Error> {
+    async fn insert_calendar(&self, calendar: Calendar) -> Result<(), Error> {
         sqlx::query!(
             r#"INSERT INTO calendars (principal, id, displayname, description, "order", color, timezone)
                 VALUES (?, ?, ?, ?, ?, ?, ?)"#,
@@ -117,7 +117,7 @@ impl CalendarStore for SqliteStore {
 
     #[instrument]
     async fn update_calendar(
-        &mut self,
+        &self,
         principal: String,
         id: String,
         calendar: Calendar,
@@ -144,7 +144,7 @@ impl CalendarStore for SqliteStore {
     // Does not actually delete the calendar but just disables it
     #[instrument]
     async fn delete_calendar(
-        &mut self,
+        &self,
         principal: &str,
         id: &str,
         use_trashbin: bool,
@@ -172,7 +172,7 @@ impl CalendarStore for SqliteStore {
     }
 
     #[instrument]
-    async fn restore_calendar(&mut self, principal: &str, id: &str) -> Result<(), Error> {
+    async fn restore_calendar(&self, principal: &str, id: &str) -> Result<(), Error> {
         sqlx::query!(
             r"UPDATE calendars SET deleted_at = NULL WHERE (principal, id) = (?, ?)",
             principal,
@@ -223,10 +223,12 @@ impl CalendarStore for SqliteStore {
 
     #[instrument]
     async fn put_object(
-        &mut self,
+        &self,
         principal: String,
         cal_id: String,
         object: CalendarObject,
+        // TODO: implement
+        overwrite: bool,
     ) -> Result<(), Error> {
         let mut tx = self.db.begin().await?;
 
@@ -257,7 +259,7 @@ impl CalendarStore for SqliteStore {
 
     #[instrument]
     async fn delete_object(
-        &mut self,
+        &self,
         principal: &str,
         cal_id: &str,
         id: &str,
@@ -300,7 +302,7 @@ impl CalendarStore for SqliteStore {
 
     #[instrument]
     async fn restore_object(
-        &mut self,
+        &self,
         principal: &str,
         cal_id: &str,
         object_id: &str,
diff --git a/crates/store/src/timestamp.rs b/crates/store/src/timestamp.rs
index 3ded9c2..93e66c2 100644
--- a/crates/store/src/timestamp.rs
+++ b/crates/store/src/timestamp.rs
@@ -92,7 +92,7 @@ impl CalDateTime {
                     if let Ok(tz) = olson_name.parse::<Tz>() {
                         Some(tz)
                     } else {
-                        return Err(Error::InvalidIcs(format!(
+                        return Err(Error::InvalidData(format!(
                             "Timezone has X-LIC-LOCATION property to specify a timezone from the Olson database, however it's value {olson_name} is invalid"
                         )));
                     }
@@ -109,7 +109,7 @@ impl CalDateTime {
                 }
             } else {
                 // TZID refers to timezone that does not exist
-                return Err(Error::InvalidIcs(format!(
+                return Err(Error::InvalidData(format!(
                     "No timezone specified with TZID={tzid}"
                 )));
             }
@@ -167,7 +167,7 @@ impl From<CalDateTime> for DateTime<Utc> {
 pub fn parse_duration(string: &str) -> Result<Duration, Error> {
     let captures = RE_DURATION
         .captures(string)
-        .ok_or(Error::InvalidIcs("Invalid duration format".to_owned()))?;
+        .ok_or(Error::InvalidData("Invalid duration format".to_owned()))?;
 
     let mut duration = Duration::zero();
     if let Some(weeks) = captures.name("W") {
diff --git a/src/app.rs b/src/app.rs
index 4116692..d23e1a1 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -6,12 +6,11 @@ use rustical_frontend::configure_frontend;
 use rustical_store::auth::AuthenticationProvider;
 use rustical_store::{AddressbookStore, CalendarStore};
 use std::sync::Arc;
-use tokio::sync::RwLock;
 use tracing_actix_web::TracingLogger;
 
 pub fn make_app<AS: AddressbookStore + ?Sized, CS: CalendarStore + ?Sized>(
-    addr_store: Arc<RwLock<AS>>,
-    cal_store: Arc<RwLock<CS>>,
+    addr_store: Arc<AS>,
+    cal_store: Arc<CS>,
     auth_provider: Arc<impl AuthenticationProvider>,
 ) -> App<
     impl ServiceFactory<
diff --git a/src/main.rs b/src/main.rs
index b1be647..d9db7a4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -19,7 +19,6 @@ use rustical_store::{AddressbookStore, CalendarStore};
 use std::fs;
 use std::sync::Arc;
 use std::time::Duration;
-use tokio::sync::RwLock;
 use tracing::level_filters::LevelFilter;
 use tracing_opentelemetry::OpenTelemetryLayer;
 use tracing_subscriber::layer::SubscriberExt;
@@ -41,14 +40,11 @@ struct Args {
 async fn get_data_stores(
     migrate: bool,
     config: &DataStoreConfig,
-) -> Result<(
-    Arc<RwLock<dyn AddressbookStore>>,
-    Arc<RwLock<dyn CalendarStore>>,
-)> {
+) -> Result<(Arc<dyn AddressbookStore>, Arc<dyn CalendarStore>)> {
     Ok(match &config {
         DataStoreConfig::Sqlite(SqliteDataStoreConfig { db_url }) => {
             let db = create_db_pool(db_url, migrate).await?;
-            let sqlite_store = Arc::new(RwLock::new(SqliteStore::new(db)));
+            let sqlite_store = Arc::new(SqliteStore::new(db));
             (sqlite_store.clone(), sqlite_store.clone())
         }
     })