diff --git a/plugins/domains/commands b/plugins/domains/commands
index 3836f90e3..05f6758f6 100755
--- a/plugins/domains/commands
+++ b/plugins/domains/commands
@@ -54,7 +54,7 @@ case "$1" in
       exit 1
     fi
 
-    if [[ $(grep $3 "$DOKKU_ROOT/$APP/VHOST" > /dev/null 2>&1; echo $?) -eq 0 ]]; then
+    if [[ $(egrep ^"$3"$ "$DOKKU_ROOT/$APP/VHOST" > /dev/null 2>&1; echo $?) -eq 0 ]]; then
       echo "$3 is already defined for $APP"
       exit 1
     fi