diff --git a/environment.c b/environment.c
index c44a30be3e..de5581fe51 100644
--- a/environment.c
+++ b/environment.c
@@ -87,8 +87,10 @@ const char * const local_repo_env[LOCAL_REPO_ENV_SIZE + 1] = {
 static void setup_git_env(void)
 {
 	git_dir = getenv(GIT_DIR_ENVIRONMENT);
-	if (!git_dir)
+	if (!git_dir) {
 		git_dir = read_gitfile_gently(DEFAULT_GIT_DIR_ENVIRONMENT);
+		git_dir = git_dir ? xstrdup(git_dir) : NULL;
+	}
 	if (!git_dir)
 		git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
 	git_object_dir = getenv(DB_ENVIRONMENT);