diff --git a/automated/build.sh b/automated/build.sh
index 14997464..adb4db9b 100755
--- a/automated/build.sh
+++ b/automated/build.sh
@@ -104,7 +104,7 @@ ARGS_BUILD="$ARGS_COMMON"
 ARGS_UPLOAD="$ARGS_COMMON -u $USERID -e HOME=$C_HOME -v $HACKAGE_CREDS:/hackage-creds:ro -v $DOT_STACKAGE_DIR:$C_HOME/.stackage -v $SSH_DIR:$C_HOME/.ssh:ro -v $GITCONFIG:$C_HOME/.gitconfig:ro -e AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY ${AWS_ENDPOINT_URL:+-e AWS_ENDPOINT_URL=$AWS_ENDPOINT_URL} -v $DOT_STACKAGE_DIR:/dot-stackage"
 
 # for debugging etc
-if [ -n = "$2" ]
+if [ -n = "${2:-}" ]
 then
   docker run -it $ARGS_UPLOAD $IMAGE $2
   exit 0