diff --git a/Dockerfile b/Dockerfile
index 52a9328..aebba32 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,8 +6,8 @@ LABEL maintainer="Robert Kaussow <mail@geeklabor.de>" \
     org.label-schema.vendor="Robert Kaussow" \
     org.label-schema.schema-version="1.0"
 
-ARG BUILD_VERSION=20.6.30
-ENV VALIDATOR_VERSION="${BUILD_VERSION}"
+ARG BUILD_VERSION
+ENV VALIDATOR_VERSION="${BUILD_VERSION:-20.6.30}"
 
 RUN apk add --update --no-cache --virtual .build-deps libarchive-tools curl && \
     apk --update add openjdk8 && \