diff --git a/core/chain_indexer_test.go b/core/chain_indexer_test.go
index f099609015..bf3bde756c 100644
--- a/core/chain_indexer_test.go
+++ b/core/chain_indexer_test.go
@@ -228,7 +228,7 @@ func (b *testChainIndexBackend) Process(ctx context.Context, header *types.Heade
 		b.t.Error("Unexpected call to Process")
 		// Can't use Fatal since this is not the test's goroutine.
 		// Returning error stops the chainIndexer's updateLoop
-		return errors.New("Unexpected call to Process")
+		return errors.New("unexpected call to Process")
 	case b.processCh <- header.Number.Uint64():
 	}
 	return nil