diff --git a/scripts/custom-docker-build b/scripts/custom-docker-build
index 56cd17b..deab923 100755
--- a/scripts/custom-docker-build
+++ b/scripts/custom-docker-build
@@ -167,7 +167,12 @@ function parse_arguments() {
 
     # Lock Ruby to Debian Buster 
     case "$base" in
-        ruby) base_version="$base_version-buster" ;;
+        ruby)
+                case "$base_version" in
+                        2.7.0) base_version="$base_version-buster" ;;
+                        *) base_version="$base_version-stretch" ;;
+                esac
+                ;;
     esac
 
     printf -- "-f Dockerfile.custom " "$base"