diff --git a/consensus/bor/api.go b/consensus/bor/api.go
index b7ffebaf66..1a2d140b21 100644
--- a/consensus/bor/api.go
+++ b/consensus/bor/api.go
@@ -54,9 +54,9 @@ type BlockSigners struct {
 
 // GetSnapshotProposerSequence retrieves the in-turn signers of all sprints in a span
 func (api *API) GetSnapshotProposerSequence(number *rpc.BlockNumber) (BlockSigners, error) {
-	*number -= 1
+	snapNumber := *number - 1
 	var difficulties = make(map[common.Address]uint64)
-	snap, err := api.GetSnapshot(number)
+	snap, err := api.GetSnapshot(&snapNumber)
 	if err != nil {
 		return BlockSigners{}, err
 	}