diff --git a/src/ray/gcs/redis_gcs_client.h b/src/ray/gcs/redis_gcs_client.h
index 57e3ac515..0d00b1e77 100644
--- a/src/ray/gcs/redis_gcs_client.h
+++ b/src/ray/gcs/redis_gcs_client.h
@@ -99,7 +99,7 @@ class RAY_EXPORT RedisGcsClient : public GcsClient {
   HeartbeatBatchTable &heartbeat_batch_table();
   DynamicResourceTable &resource_table();
   /// Implements the Tasks() interface.
-  raylet::TaskTable &raylet_task_table();
+  virtual raylet::TaskTable &raylet_task_table();
   TaskLeaseTable &task_lease_table();
   TaskReconstructionLog &task_reconstruction_log();
   /// Implements the Errors() interface.
diff --git a/src/ray/raylet/lineage_cache_test.cc b/src/ray/raylet/lineage_cache_test.cc
index 4bd895d71..196a66fb8 100644
--- a/src/ray/raylet/lineage_cache_test.cc
+++ b/src/ray/raylet/lineage_cache_test.cc
@@ -157,7 +157,7 @@ class MockGcsClient : public gcs::RedisGcsClient {
     node_accessor_.reset(new MockNodeInfoAccessor(this, node_id));
   }
 
-  gcs::raylet::TaskTable &raylet_task_table() { return *task_table_fake_; }
+  gcs::raylet::TaskTable &raylet_task_table() override { return *task_table_fake_; }
 
   MockTaskInfoAccessor &MockTasks() {
     return *dynamic_cast<MockTaskInfoAccessor *>(task_accessor_.get());