diff --git a/pkg/compute/models/instance_snapshots.go b/pkg/compute/models/instance_snapshots.go
index b28befb81b..75ec98098a 100644
--- a/pkg/compute/models/instance_snapshots.go
+++ b/pkg/compute/models/instance_snapshots.go
@@ -239,7 +239,7 @@ func (self *SInstanceSnapshot) getMoreDetails(userCred mcclient.TokenCredential,
 				out.StorageType = snapshots[i].GetStorageType()
 			}
 		}
-	} else {
+	} else if guest != nil {
 		out.Size = self.SizeMb
 		disk, err := guest.GetSystemDisk()
 		if err != nil {