diff --git a/build-docker.sh b/build-docker.sh
index 9538a8b..01fd517 100755
--- a/build-docker.sh
+++ b/build-docker.sh
@@ -48,6 +48,7 @@ fi
 CONTAINER_NAME=${CONTAINER_NAME:-pigen_work}
 CONTINUE=${CONTINUE:-0}
 PRESERVE_CONTAINER=${PRESERVE_CONTAINER:-0}
+PIGEN_DOCKER_OPTS=${PIGEN_DOCKER_OPTS:-""}  
 
 if [ -z "${IMG_NAME}" ]; then
 	echo "IMG_NAME not set in 'config'" 1>&2