diff --git a/filter.go b/filter.go
index 7079b82..55be956 100644
--- a/filter.go
+++ b/filter.go
@@ -73,20 +73,14 @@ type SeqFilter struct {
 func convertQuestionMark(sql, prefix string, start int) string {
 	var buf strings.Builder
 	var beginSingleQuote bool
-	var beginTransfer bool
 	var index = start
 	for _, c := range sql {
 		if !beginSingleQuote && c == '?' {
 			buf.WriteString(fmt.Sprintf("%s%v", prefix, index))
 			index++
 		} else {
-			if c == '\\' {
-				beginTransfer = true
-			} else {
-				if !beginTransfer && c == '\'' {
-					beginSingleQuote = !beginSingleQuote
-				}
-				beginTransfer = false
+			if c == '\'' {
+				beginSingleQuote = !beginSingleQuote
 			}
 			buf.WriteRune(c)
 		}
diff --git a/filter_test.go b/filter_test.go
index 54a1cf6..a6b7b3b 100644
--- a/filter_test.go
+++ b/filter_test.go
@@ -28,7 +28,10 @@ func TestSeqFilter(t *testing.T) {
 	var kases = map[string]string{
 		"SELECT * FROM TABLE1 WHERE a=? AND b=?":                               "SELECT * FROM TABLE1 WHERE a=$1 AND b=$2",
 		"SELECT 1, '???', '2006-01-02 15:04:05' FROM TABLE1 WHERE a=? AND b=?": "SELECT 1, '???', '2006-01-02 15:04:05' FROM TABLE1 WHERE a=$1 AND b=$2",
-		"select '1\\'?' from issue":                                            "select '1\\'?' from issue",
+		"select '1''?' from issue":                                             "select '1''?' from issue",
+		"select '1\\??' from issue":                                            "select '1\\??' from issue",
+		"select '1\\\\',? from issue":                                          "select '1\\\\',$1 from issue",
+		"select '1\\''?',? from issue":                                         "select '1\\''?',$1 from issue",
 	}
 	for sql, result := range kases {
 		assert.EqualValues(t, result, convertQuestionMark(sql, "$", 1))