diff --git a/server/cmd_zset.go b/server/cmd_zset.go
index eb25073..e8e8014 100644
--- a/server/cmd_zset.go
+++ b/server/cmd_zset.go
@@ -120,17 +120,18 @@ func zparseScoreRange(minBuf []byte, maxBuf []byte) (min int64, max int64, err e
 	if strings.ToLower(ledis.String(minBuf)) == "-inf" {
 		min = math.MinInt64
 	} else {
-		var lopen bool = false
-		if minBuf[0] == '(' {
-			lopen = true
-			minBuf = minBuf[1:]
-		}
 
 		if len(minBuf) == 0 {
 			err = ErrCmdParams
 			return
 		}
 
+		var lopen bool = false
+		if minBuf[0] == '(' {
+			lopen = true
+			minBuf = minBuf[1:]
+		}
+
 		min, err = ledis.StrInt64(minBuf, nil)
 		if err != nil {
 			return
@@ -150,16 +151,17 @@ func zparseScoreRange(minBuf []byte, maxBuf []byte) (min int64, max int64, err e
 		max = math.MaxInt64
 	} else {
 		var ropen = false
-		if maxBuf[0] == '(' {
-			ropen = true
-			maxBuf = maxBuf[1:]
-		}
 
 		if len(maxBuf) == 0 {
 			err = ErrCmdParams
 			return
 		}
 
+		if maxBuf[0] == '(' {
+			ropen = true
+			maxBuf = maxBuf[1:]
+		}
+
 		max, err = ledis.StrInt64(maxBuf, nil)
 		if err != nil {
 			return