diff --git a/main/utils.c b/main/utils.c
index 320516e332935516fea8b552527086b1cc7ec17b..25de47ef3d82f7b885f4d427445f636aab477845 100644
--- a/main/utils.c
+++ b/main/utils.c
@@ -742,13 +742,16 @@ static char *handle_show_locks(struct ast_cli_entry *e, int cmd, struct ast_cli_
 	               "=== <file> <line num> <function> <lock name> <lock addr> (times locked)\n"
 	               "===\n");
 
+	if (!str)
+		return CLI_FAILURE;
+
 	pthread_mutex_lock(&lock_infos_lock.mutex);
 	AST_LIST_TRAVERSE(&lock_infos, lock_info, entry) {
 		int i;
 		ast_str_append(&str, 0, "=== Thread ID: %d (%s)\n", (int) lock_info->thread_id,
 			lock_info->thread_name);
 		pthread_mutex_lock(&lock_info->lock);
-		for (i = 0; i < lock_info->num_locks; i++) {
+		for (i = 0; str && i < lock_info->num_locks; i++) {
 			ast_str_append(&str, 0, "=== ---> %sLock #%d (%s): %s %d %s %s %p (%d)\n", 
 				lock_info->locks[i].pending > 0 ? "Waiting for " : 
 					lock_info->locks[i].pending < 0 ? "Tried and failed to get " : "", i,
@@ -760,19 +763,29 @@ static char *handle_show_locks(struct ast_cli_entry *e, int cmd, struct ast_cli_
 				lock_info->locks[i].times_locked);
 		}
 		pthread_mutex_unlock(&lock_info->lock);
+		if (!str)
+			break;
 		ast_str_append(&str, 0, "=== -------------------------------------------------------------------\n"
 		               "===\n");
+		if (!str)
+			break;
 	}
 	pthread_mutex_unlock(&lock_infos_lock.mutex);
 
+	if (!str)
+		return CLI_FAILURE;
+
 	ast_str_append(&str, 0, "=======================================================================\n"
 	               "\n");
 
+	if (!str)
+		return CLI_FAILURE;
+
 	ast_cli(a->fd, "%s", str->str);
 
 	free(str);
 
-	return 0;
+	return CLI_SUCCESS;
 }
 
 static struct ast_cli_entry utils_cli[] = {