diff --git a/consensus/XDPoS/api.go b/consensus/XDPoS/api.go
index 0dbcb897f3..570868a45f 100644
--- a/consensus/XDPoS/api.go
+++ b/consensus/XDPoS/api.go
@@ -468,7 +468,7 @@ func (api *API) getRewardFileNamesInRange(begin, end *rpc.BlockNumber) ([]reward
 	startIndex := sort.SearchInts(epochNumbers, int(beginHeader.Number.Int64()))
 	endIndex := sort.SearchInts(epochNumbers, int(endHeader.Number.Int64()))
 	if endIndex == len(epochNumbers) {
-		endIndex = endIndex - 1  //this is to prevent endIndex out of bounds when endInput is higher than last reward(epoch) block but lower than latest block
+		endIndex--  //this is to prevent endIndex out of bounds when endInput is higher than last reward(epoch) block but lower than latest block
 	}
 
 	var rewardfileNamesInRange []rewardFileName