diff --git a/savevm.c b/savevm.c
index 60d2f2a..d1b9b4a 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2021,6 +2021,8 @@
     if (ret < 0) {
         return ret;
     } else if (sn.vm_state_size == 0) {
+        error_report("This is a disk-only snapshot. Revert to it offline "
+            "using qemu-img.");
         return -EINVAL;
     }