diff --git a/git-sh-setup.sh b/git-sh-setup.sh
index d56426dd39..5e22440aec 100755
--- a/git-sh-setup.sh
+++ b/git-sh-setup.sh
@@ -128,7 +128,7 @@ cd_to_toplevel () {
 }
 
 require_work_tree () {
-	test $(git rev-parse --is-inside-work-tree) = true ||
+	test "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = true ||
 	die "fatal: $0 cannot be used without a working tree."
 }