diff --git a/lib/repository.c b/lib/repository.c
index 71d7edd4ce..1f1ff56a42 100644
--- a/lib/repository.c
+++ b/lib/repository.c
@@ -154,7 +154,7 @@ static void repo_set_commondir(struct repository *repo,
 {
 	struct strbuf sb = STRBUF_INIT;
 
-	free(repo->commondir);
+	FREE_AND_NULL(repo->commondir);
 
 	if (commondir) {
 		repo->different_commondir = 1;