diff --git a/eth/backend_test.go b/eth/backend_test.go
index d91045649d..1b628a00b0 100644
--- a/eth/backend_test.go
+++ b/eth/backend_test.go
@@ -8,16 +8,19 @@ import (
 
 func TestRewardInflation(t *testing.T) {
 	for i := 0; i < 100; i++ {
+		// the first 2 years
 		chainReward := new(big.Int).Mul(new(big.Int).SetUint64(250), new(big.Int).SetUint64(params.Ether))
 		chainReward = rewardInflation(chainReward, uint64(i), 10)
 
+		// 3rd year, 4th year, 5th year
 		halfReward := new(big.Int).Mul(new(big.Int).SetUint64(125), new(big.Int).SetUint64(params.Ether))
-		if 20 <= i && i < 60 && chainReward.Cmp(halfReward) != 0 {
+		if 20 <= i && i < 50 && chainReward.Cmp(halfReward) != 0 {
 			t.Error("Fail tor calculate reward inflation for 2 -> 5 years", "chainReward", chainReward)
 		}
 
+		// after 5 years
 		quarterReward := new(big.Int).Mul(new(big.Int).SetUint64(62.5*1000), new(big.Int).SetUint64(params.Finney))
-		if 60 <= i && chainReward.Cmp(quarterReward) != 0 {
+		if 50 <= i && chainReward.Cmp(quarterReward) != 0 {
 			t.Error("Fail tor calculate reward inflation above 6 years", "chainReward", chainReward)
 		}
 	}