diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 8866af2250..7e2ffd8869 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -1563,7 +1563,9 @@ static int add_possible_reference_from_superproject(
 
 		sm_alternate = compute_alternate_path(sb.buf, &err);
 		if (sm_alternate) {
-			string_list_append(sas->reference, xstrdup(sb.buf));
+			char *p = strbuf_detach(&sb, NULL);
+
+			string_list_append(sas->reference, p)->util = p;
 			free(sm_alternate);
 		} else {
 			switch (sas->error_mode) {
@@ -1795,6 +1797,7 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 
 	clone_submodule(&clone_data, &reference);
 	list_objects_filter_release(&filter_options);
+	string_list_clear(&reference, 1);
 	return 0;
 }
 
@@ -3042,6 +3045,7 @@ static int add_submodule(const struct add_data *add_data)
 	char *submod_gitdir_path;
 	struct module_clone_data clone_data = MODULE_CLONE_DATA_INIT;
 	struct string_list reference = STRING_LIST_INIT_NODUP;
+	int ret = -1;
 
 	/* perhaps the path already exists and is already a git repo, else clone it */
 	if (is_directory(add_data->sm_path)) {
@@ -3097,15 +3101,17 @@ static int add_submodule(const struct add_data *add_data)
 		clone_data.url = add_data->realrepo;
 		clone_data.quiet = add_data->quiet;
 		clone_data.progress = add_data->progress;
-		if (add_data->reference_path)
-			string_list_append(&reference,
-					   xstrdup(add_data->reference_path));
+		if (add_data->reference_path) {
+			char *p = xstrdup(add_data->reference_path);
+
+			string_list_append(&reference, p)->util = p;
+		}
 		clone_data.dissociate = add_data->dissociate;
 		if (add_data->depth >= 0)
 			clone_data.depth = xstrfmt("%d", add_data->depth);
 
 		if (clone_submodule(&clone_data, &reference))
-			return -1;
+			goto cleanup;
 
 		prepare_submodule_repo_env(&cp.env);
 		cp.git_cmd = 1;
@@ -3124,7 +3130,10 @@ static int add_submodule(const struct add_data *add_data)
 		if (run_command(&cp))
 			die(_("unable to checkout submodule '%s'"), add_data->sm_path);
 	}
-	return 0;
+	ret = 0;
+cleanup:
+	string_list_clear(&reference, 1);
+	return ret;
 }
 
 static int config_submodule_in_gitmodules(const char *name, const char *var, const char *value)