diff --git a/weed/ec/ec_decode.go b/weed/ec/ec_decode.go
index 985b522c5d..b0c3c2ef6c 100644
--- a/weed/ec/ec_decode.go
+++ b/weed/ec/ec_decode.go
@@ -26,6 +26,12 @@ func DoEcDecode(env *Env, topoInfo *master_pb.TopologyInfo, collection string, v
 		return fmt.Errorf("lock is lost")
 	}
 
+	if collection == "" {
+		if c, found := FindEcVolumeCollection(topoInfo, vid); found {
+			collection = c
+		}
+	}
+
 	// find volume location
 	nodeToEcShardsInfo, dataShards := collectEcNodeShardsInfo(topoInfo, vid)
 
@@ -376,6 +382,33 @@ func CollectEcShardIds(topoInfo *master_pb.TopologyInfo, collectionMatcher *wild
 	return
 }
 
+// FindEcVolumeCollection returns the collection of the ec volume's shards.
+func FindEcVolumeCollection(topoInfo *master_pb.TopologyInfo, vid needle.VolumeId) (string, bool) {
+	if topoInfo == nil {
+		return "", false
+	}
+	var collection string
+	var found bool
+	EachDataNode(topoInfo, func(dc DataCenterId, rack RackId, dn *master_pb.DataNodeInfo) {
+		if found {
+			return
+		}
+		for _, diskInfo := range dn.DiskInfos {
+			if diskInfo == nil {
+				continue
+			}
+			for _, v := range diskInfo.EcShardInfos {
+				if v.Id == uint32(vid) {
+					collection = v.Collection
+					found = true
+					return
+				}
+			}
+		}
+	})
+	return collection, found
+}
+
 func collectEcNodeShardsInfo(topoInfo *master_pb.TopologyInfo, vid needle.VolumeId) (map[pb.ServerAddress]*erasure_coding.ShardsInfo, int) {
 	res := make(map[pb.ServerAddress]*erasure_coding.ShardsInfo)
 	EachDataNode(topoInfo, func(dc DataCenterId, rack RackId, dn *master_pb.DataNodeInfo) {
diff --git a/weed/ec/ec_decode_test.go b/weed/ec/ec_decode_test.go
index bf73126e86..ae69a11fdb 100644
--- a/weed/ec/ec_decode_test.go
+++ b/weed/ec/ec_decode_test.go
@@ -4,7 +4,9 @@ import (
 	"testing"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
 	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
 )
 
 // shardsOn builds one holder's inventory.
@@ -89,3 +91,99 @@ func TestMissingDataShard(t *testing.T) {
 		})
 	}
 }
+
+func TestFindEcVolumeCollection(t *testing.T) {
+	topo := &master_pb.TopologyInfo{
+		DataCenterInfos: []*master_pb.DataCenterInfo{
+			{
+				Id: "dc1",
+				RackInfos: []*master_pb.RackInfo{
+					{
+						Id: "rack1",
+						DataNodeInfos: []*master_pb.DataNodeInfo{
+							{
+								Id: "node1",
+								DiskInfos: map[string]*master_pb.DiskInfo{
+									"hdd": {
+										EcShardInfos: []*master_pb.VolumeEcShardInformationMessage{
+											{
+												Id:         10,
+												Collection: "s3bucket",
+											},
+											{
+												Id:         30,
+												Collection: "",
+											},
+										},
+										VolumeInfos: []*master_pb.VolumeInformationMessage{
+											{
+												Id:         20,
+												Collection: "regular_col",
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	tests := []struct {
+		name      string
+		topo      *master_pb.TopologyInfo
+		vid       needle.VolumeId
+		wantCol   string
+		wantFound bool
+	}{
+		{
+			name:      "nil topology",
+			topo:      nil,
+			vid:       10,
+			wantCol:   "",
+			wantFound: false,
+		},
+		{
+			name:      "ec volume with named collection",
+			topo:      topo,
+			vid:       10,
+			wantCol:   "s3bucket",
+			wantFound: true,
+		},
+		{
+			name:      "ec volume with empty collection",
+			topo:      topo,
+			vid:       30,
+			wantCol:   "",
+			wantFound: true,
+		},
+		{
+			name:      "regular volume record is not an ec volume",
+			topo:      topo,
+			vid:       20,
+			wantCol:   "",
+			wantFound: false,
+		},
+		{
+			name:      "not found",
+			topo:      topo,
+			vid:       999,
+			wantCol:   "",
+			wantFound: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			col, found := FindEcVolumeCollection(tt.topo, tt.vid)
+			if found != tt.wantFound {
+				t.Fatalf("FindEcVolumeCollection() found = %v, want %v", found, tt.wantFound)
+			}
+			if col != tt.wantCol {
+				t.Errorf("FindEcVolumeCollection() col = %q, want %q", col, tt.wantCol)
+			}
+		})
+	}
+}
diff --git a/weed/shell/command_ec_decode.go b/weed/shell/command_ec_decode.go
index 33e640d182..a33a46c4af 100644
--- a/weed/shell/command_ec_decode.go
+++ b/weed/shell/command_ec_decode.go
@@ -113,7 +113,9 @@ func (c *commandEcDecode) Do(args []string, commandEnv *CommandEnv, writer io.Wr
 			fmt.Printf("ec decode batch %d/%d: %v\n", i+1, len(batches), batch)
 		}
 		for _, vid := range batch {
-			if err = ec.DoEcDecode(env, topologyInfo, *collection, vid, diskType, *checkMinFreeSpace, diskUsageState); err != nil {
+			// -collection is a selector, not the volume's collection
+			volumeCollection, _ := ec.FindEcVolumeCollection(topologyInfo, vid)
+			if err = ec.DoEcDecode(env, topologyInfo, volumeCollection, vid, diskType, *checkMinFreeSpace, diskUsageState); err != nil {
 				return err
 			}
 		}