diff --git a/weed/storage/store_ec.go b/weed/storage/store_ec.go
index eb10e5ae1..5a718f316 100644
--- a/weed/storage/store_ec.go
+++ b/weed/storage/store_ec.go
@@ -87,7 +87,7 @@ func (s *Store) MountEcShards(collection string, vid needle.VolumeId, shardId er
 
 func (s *Store) UnmountEcShards(vid needle.VolumeId, shardId erasure_coding.ShardId, generation uint32) error {
 
-	diskId, ecShard, found := s.findEcShard(vid, shardId)
+	diskId, ecShard, found := s.findEcShardWithGeneration(vid, shardId, generation)
 	if !found {
 		return nil
 	}
@@ -122,6 +122,15 @@ func (s *Store) findEcShard(vid needle.VolumeId, shardId erasure_coding.ShardId)
 	return 0, nil, false
 }
 
+func (s *Store) findEcShardWithGeneration(vid needle.VolumeId, shardId erasure_coding.ShardId, generation uint32) (diskId uint32, shard *erasure_coding.EcVolumeShard, found bool) {
+	for diskId, location := range s.Locations {
+		if v, found := location.FindEcShardWithGeneration(vid, shardId, generation); found {
+			return uint32(diskId), v, found
+		}
+	}
+	return 0, nil, false
+}
+
 func (s *Store) FindEcVolume(vid needle.VolumeId) (*erasure_coding.EcVolume, bool) {
 	for _, location := range s.Locations {
 		if s, found := location.FindEcVolume(vid); found {