diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index e6f2399efc..c635fc8820 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -232,6 +232,7 @@ static int load_capng(void)
          */
         cap.saved = capng_save_state();
         if (!cap.saved) {
+            pthread_mutex_unlock(&cap.mutex);
             fuse_log(FUSE_LOG_ERR, "capng_save_state (thread)\n");
             return -EINVAL;
         }