diff --git a/plugins/hg612_errors b/plugins/hg612_errors
index 9fd0985..a29e60d 100755
--- a/plugins/hg612_errors
+++ b/plugins/hg612_errors
@@ -37,7 +37,7 @@ if [ "$1" = "config" ]; then
 
 	echo "graph_title Errors"
 	echo "graph_args --base 1000"
-	echo "graph_vlabel errors down (-) / up (+) per ${graph_period}"
+	echo 'graph_vlabel errors down (-) / up (+) per ${graph_period}'
 	echo "graph_category hg612"
 	echo "graph_scale no"
 
diff --git a/plugins/hg612_ptm1 b/plugins/hg612_ptm1
index e4c0bd7..6fe7d04 100755
--- a/plugins/hg612_ptm1
+++ b/plugins/hg612_ptm1
@@ -37,7 +37,7 @@ if [ "$1" = "config" ]; then
 
 	echo "graph_title ptm1 traffic"
 	echo "graph_args --base 1000"
-	echo "graph_vlabel bytes per ${graph_period}"
+	echo 'graph_vlabel bytes per ${graph_period}'
 	echo "graph_category hg612"
 	echo "down.label received"
 	echo "down.type DERIVE"