diff --git a/tests/difficulty_test.go b/tests/difficulty_test.go
index 6006373009..20294cc9d5 100644
--- a/tests/difficulty_test.go
+++ b/tests/difficulty_test.go
@@ -27,7 +27,7 @@ import (
 
 var (
 	mainnetChainConfig = params.ChainConfig{
-		ChainId:        big.NewInt(1),
+		ChainID:        big.NewInt(1),
 		HomesteadBlock: big.NewInt(1150000),
 		DAOForkBlock:   big.NewInt(1920000),
 		DAOForkSupport: true,