diff --git a/crates/caldav/src/calendar/resource.rs b/crates/caldav/src/calendar/resource.rs
index 1d3eedc..4165593 100644
--- a/crates/caldav/src/calendar/resource.rs
+++ b/crates/caldav/src/calendar/resource.rs
@@ -359,7 +359,7 @@ impl<C: CalendarStore, S: SubscriptionStore> ResourceService for CalendarResourc
             .into_iter()
             .map(|object| {
                 (
-                    object.get_id().to_string(),
+                    format!("{}.ics", object.get_id()),
                     CalendarObjectResource {
                         object,
                         principal: principal.to_owned(),
diff --git a/crates/carddav/src/addressbook/resource.rs b/crates/carddav/src/addressbook/resource.rs
index 1488448..f805ff5 100644
--- a/crates/carddav/src/addressbook/resource.rs
+++ b/crates/carddav/src/addressbook/resource.rs
@@ -228,7 +228,7 @@ impl<AS: AddressbookStore, S: SubscriptionStore> ResourceService
             .into_iter()
             .map(|object| {
                 (
-                    object.get_id().to_string(),
+                    format!("{}.vcf", object.get_id()),
                     AddressObjectResource {
                         object,
                         principal: principal.to_owned(),