diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
index 0fa6faa..596203a 100755
--- a/build-aux/git-version-gen
+++ b/build-aux/git-version-gen
@@ -129,7 +129,11 @@ v=`echo "$v" |sed 's/^v//'`
 # Don't declare a version "dirty" merely because a time stamp has changed.
 git status > /dev/null 2>&1
 
-dirty=`sh -c 'git diff-index --name-only HEAD' 2>/dev/null` || dirty=
+if [ -d .git ]; then
+	dirty=`sh -c 'git diff-index --name-only HEAD' 2>/dev/null` || dirty=
+else
+	dirty=
+fi
 case "$dirty" in
     '') ;;
     *) # Append the suffix only if there isn't one already.