diff --git a/database/string_test.go b/database/string_test.go
index d1a379d..10bd114 100644
--- a/database/string_test.go
+++ b/database/string_test.go
@@ -25,6 +25,20 @@ func TestSet2(t *testing.T) {
 	}
 }
 
+func TestSetEmpty(t *testing.T) {
+	key := utils.RandString(10)
+	testDB.Exec(nil, utils.ToCmdLine("SET", key, ""))
+	actual := testDB.Exec(nil, utils.ToCmdLine("GET", key))
+	bulkReply, ok := actual.(*protocol.BulkReply)
+	if !ok {
+		t.Errorf("expected bulk protocol, actually %s", actual.ToBytes())
+		return
+	}
+	if !(bulkReply.Arg != nil && len(bulkReply.Arg) == 0) {
+		t.Error("illegal empty string")
+	}
+}
+
 func TestSet(t *testing.T) {
 	testDB.Flush()
 	key := utils.RandString(10)
diff --git a/redis/parser/parser.go b/redis/parser/parser.go
index 2ac6ed7..e22286c 100644
--- a/redis/parser/parser.go
+++ b/redis/parser/parser.go
@@ -240,7 +240,7 @@ func parseBulkHeader(msg []byte, state *readState) error {
 	}
 	if state.bulkLen == -1 { // null bulk
 		return nil
-	} else if state.bulkLen > 0 {
+	} else if state.bulkLen >= 0 {
 		state.msgType = msg[0]
 		state.readingMultiLine = true
 		state.expectedArgsCount = 1
@@ -281,13 +281,13 @@ func parseSingleLineReply(msg []byte) (redis.Reply, error) {
 func readBody(msg []byte, state *readState) error {
 	line := msg[0 : len(msg)-2]
 	var err error
-	if line[0] == '$' {
+	if len(line) > 0 && line[0] == '$' {
 		// bulk protocol
 		state.bulkLen, err = strconv.ParseInt(string(line[1:]), 10, 64)
 		if err != nil {
 			return errors.New("protocol error: " + string(msg))
 		}
-		if state.bulkLen <= 0 { // null bulk in multi bulks
+		if state.bulkLen < 0 { // null bulk in multi bulks
 			state.args = append(state.args, []byte{})
 			state.bulkLen = 0
 		}
diff --git a/redis/protocol/reply.go b/redis/protocol/reply.go
index ed4bbbe..98cadb1 100644
--- a/redis/protocol/reply.go
+++ b/redis/protocol/reply.go
@@ -28,7 +28,7 @@ func MakeBulkReply(arg []byte) *BulkReply {
 
 // ToBytes marshal redis.Reply
 func (r *BulkReply) ToBytes() []byte {
-	if len(r.Arg) == 0 {
+	if r.Arg == nil {
 		return nullBulkBytes
 	}
 	return []byte("$" + strconv.Itoa(len(r.Arg)) + CRLF + string(r.Arg) + CRLF)