diff --git a/include/helper_audit_dockerfile b/include/helper_audit_dockerfile
index 273bb347..3d18556f 100644
--- a/include/helper_audit_dockerfile
+++ b/include/helper_audit_dockerfile
@@ -59,13 +59,12 @@ fi
         IS_ALPINE=$(echo ${IMAGE} | grep -i alpine)
         IS_LATEST=$(echo ${TAG} | grep -i latest)
 
-        if [ ! "${IS_DEBIAN}" = "" ]; then IMAGE="debian"; fi
-        if [ ! "${IS_FEDORA}" = "" ]; then IMAGE="fedora"; fi
-        if [ ! "${IS_UBUNTU}" = "" ]; then IMAGE="ubuntu"; fi
-        if [ ! "${IS_ALPINE}" = "" ]; then IMAGE="alpine"; fi
-        
-        if [ ! "${IS_LATEST}" = "" ]; then 
-            ReportWarning "dockerfile" "latest TAG used. Specifying the version is better."
+        if [ ! -z "${IS_DEBIAN}" ]; then IMAGE="debian"; fi
+        if [ ! -z "${IS_FEDORA}" ]; then IMAGE="fedora"; fi
+        if [ ! -z "${IS_UBUNTU}" ]; then IMAGE="ubuntu"; fi
+        if [ ! -z "${IS_ALPINE}" ]; then IMAGE="alpine"; fi
+        if [ ! -z "${IS_LATEST}" ]; then
+            ReportWarning "dockerfile" "latest TAG used. Specifying a targeted OS image and version is better for reproducible results."
         fi
 
         case ${IMAGE} in