diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index 8ddaa16ac1..b8b8457735 100755
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -11,7 +11,7 @@ LF='
 if test -f version
 then
 	VN=$(cat version) || VN="$DEF_VER"
-elif test -d .git -o -f .git &&
+elif test -d ${GIT_DIR:-.git} -o -f .git &&
 	VN=$(git describe --match "v[0-9]*" --abbrev=7 HEAD 2>/dev/null) &&
 	case "$VN" in
 	*$LF*) (exit 1) ;;