diff --git a/build-aux/git-abi-version-gen b/build-aux/git-abi-version-gen
index bf47a766f7828f8a4b77074dd4a5b378ac882e3a..5b30b1d782794f8497585a29b4ab208bf9eec96d 100755
--- a/build-aux/git-abi-version-gen
+++ b/build-aux/git-abi-version-gen
@@ -29,8 +29,11 @@ if test "${VERSION:-}" != ""; then
   :
 elif test -f version; then
   VERSION="`cat version`"
-else test -e .git;
+elif test -e .git; then
   VERSION="0.0.0"
+else
+  echo "Cannot determine version number">&2
+  exit 1
 fi
 
 mangle_version $VERSION