diff --git a/tools/meson-vcs-tag.sh b/tools/meson-vcs-tag.sh
index b0ab0978c8..4a8dc89ab2 100755
--- a/tools/meson-vcs-tag.sh
+++ b/tools/meson-vcs-tag.sh
@@ -6,7 +6,7 @@ set -o pipefail
 
 dir="${1:?}"
 fallback="${2:?}"
-version_tag="$3"
+version_tag="${3:-}"
 
 if [ -n "${version_tag}" ]; then
     # If -Dversion_tag= was used, just use that without further changes.