diff --git a/hack/release-build.sh b/hack/release-build.sh
index 20fb91d5..4d4c5614 100755
--- a/hack/release-build.sh
+++ b/hack/release-build.sh
@@ -87,19 +87,19 @@ build_builder_image() {
 
 build_env_image() {
     local version=$1
-    envdir=$2
-    imgnamebase=$3
-    imgvariant=$4
+    local envdir=$2
+    local imgnamebase=$3
+    local imgvariant=$4
 
     if [ -z "$imgvariant" ]
-    then 
+    then
         # no variant specified, just use the base name
         imgname=$imgnamebase
         dockerfile="Dockerfile"
-    else 
+    else
         # variant specified - append variant to image name and assume dockerfile 
         # exists with same suffix (e.g. image node-env-debian built from Dockerfile-debian)
-        imgname="$imgname-$imgvariant"
+        imgname="$imgnamebase-$imgvariant"
         dockerfile="Dockerfile-$imgvariant"
     fi
     echo "Building $envdir -> $imgname:$version using $dockerfile"
diff --git a/hack/release.sh b/hack/release.sh
index 4a1f0acb..dc8d8b49 100755
--- a/hack/release.sh
+++ b/hack/release.sh
@@ -90,9 +90,9 @@ push_all_envs() {
 
 push_env_builder_image() {
     local version=$1
-    envdir=$2
-    imgnamebase=$3
-    imgvariant=$4
+    local envdir=$2
+    local imgnamebase=$3
+    local imgvariant=$4
 
     if [ -z "$imgvariant" ]
     then
@@ -101,7 +101,7 @@ push_env_builder_image() {
     else
         # variant specified - append variant to image name and assume dockerfile
         # exists with same suffix (e.g. image node-env-debian built from Dockerfile-debian)
-        imgname="$imgname-$imgvariant"
+        imgname="$imgnamebase-$imgvariant"
     fi
     echo "Pushing $envdir -> $imgname:$version"