diff --git a/pkg/keyspace/keyspace.go b/pkg/keyspace/keyspace.go
index 2ec7f104fa9..3d208aef2a2 100644
--- a/pkg/keyspace/keyspace.go
+++ b/pkg/keyspace/keyspace.go
@@ -785,7 +785,9 @@ func (manager *Manager) PatrolKeyspaceAssignment(startKeyspaceID, endKeyspaceID
 		if err != nil {
 			return err
 		}
+		manager.kgm.Lock()
 		manager.kgm.groups[endpoint.StringUserKind(defaultKeyspaceGroup.UserKind)].Put(defaultKeyspaceGroup)
+		manager.kgm.Unlock()
 		// If all keyspaces in the current batch are assigned, update the next start ID.
 		manager.nextPatrolStartID = nextStartID
 	}