diff --git a/weed/topology/topology_ec.go b/weed/topology/topology_ec.go
index 30c174941..6f7189f1a 100644
--- a/weed/topology/topology_ec.go
+++ b/weed/topology/topology_ec.go
@@ -129,6 +129,10 @@ func (loc *EcShardLocations) DeleteShard(shardId erasure_coding.ShardId, dn *Dat
 
 func (t *Topology) RegisterEcShards(ecvi *erasure_coding.EcVolumeInfo, dn *DataNode) {
 
+	// EC-only volumes (source volume deleted after encoding) must bump
+	// maxVolumeId too, or a heartbeat-rebuilt master could re-issue their id.
+	t.UpAdjustMaxVolumeId(ecvi.VolumeId)
+
 	t.ecShardMapLock.Lock()
 	defer t.ecShardMapLock.Unlock()
 
diff --git a/weed/topology/topology_ec_max_volume_id_test.go b/weed/topology/topology_ec_max_volume_id_test.go
new file mode 100644
index 000000000..4ec9d9e1b
--- /dev/null
+++ b/weed/topology/topology_ec_max_volume_id_test.go
@@ -0,0 +1,50 @@
+package topology
+
+import (
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
+	"github.com/seaweedfs/seaweedfs/weed/sequence"
+	"github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
+)
+
+// TestRegisterEcShardsAdvancesMaxVolumeId guards against volume-id reuse: an
+// EC-only volume must advance maxVolumeId so a heartbeat-rebuilt master cannot
+// re-issue its id.
+func TestRegisterEcShardsAdvancesMaxVolumeId(t *testing.T) {
+	topo := NewTopology("weedfs", sequence.NewMemorySequencer(), 32*1024, 5, false)
+	dc := topo.GetOrCreateDataCenter("dc1")
+	rack := dc.GetOrCreateRack("rack1")
+	dn := rack.GetOrCreateDataNode("127.0.0.1", 34534, 0, "127.0.0.1", "", map[string]uint32{"": 100})
+
+	const ecVid = uint32(39848)
+	if got := topo.GetMaxVolumeId(); uint32(got) >= ecVid {
+		t.Fatalf("precondition: maxVolumeId already %d, want < %d", got, ecVid)
+	}
+
+	// Full-sync heartbeat reporting an EC-only volume.
+	msg := buildEcShardMessage(ecVid, "prefeitura", "", 0, []erasure_coding.ShardId{0, 1, 2, 3})
+	topo.SyncDataNodeEcShards([]*master_pb.VolumeEcShardInformationMessage{msg}, dn)
+
+	if got := topo.GetMaxVolumeId(); got != needle.VolumeId(ecVid) {
+		t.Fatalf("maxVolumeId after EC registration = %d, want %d", got, ecVid)
+	}
+}
+
+// TestIncrementalSyncDataNodeEcShardsAdvancesMaxVolumeId locks the same
+// invariant on the incremental heartbeat path.
+func TestIncrementalSyncDataNodeEcShardsAdvancesMaxVolumeId(t *testing.T) {
+	topo := NewTopology("weedfs", sequence.NewMemorySequencer(), 32*1024, 5, false)
+	dc := topo.GetOrCreateDataCenter("dc1")
+	rack := dc.GetOrCreateRack("rack1")
+	dn := rack.GetOrCreateDataNode("127.0.0.1", 34534, 0, "127.0.0.1", "", map[string]uint32{"": 100})
+
+	const ecVid = uint32(39849)
+	msg := buildEcShardMessage(ecVid, "prefeitura", "", 0, []erasure_coding.ShardId{0, 1, 2, 3})
+	topo.IncrementalSyncDataNodeEcShards([]*master_pb.VolumeEcShardInformationMessage{msg}, nil, dn)
+
+	if got := topo.GetMaxVolumeId(); got != needle.VolumeId(ecVid) {
+		t.Fatalf("maxVolumeId after incremental EC registration = %d, want %d", got, ecVid)
+	}
+}