diff --git a/fileutil/file.go b/fileutil/file.go
index 6d2752c..3a043dc 100644
--- a/fileutil/file.go
+++ b/fileutil/file.go
@@ -594,9 +594,11 @@ func WriteCsvFile(filepath string, records [][]string, append bool) error {
 // WriteStringToFile write string to target file.
 // Play: https://go.dev/play/p/GhLS6d8lH_g
 func WriteStringToFile(filepath string, content string, append bool) error {
-	flag := os.O_RDWR | os.O_CREATE
+	var flag int
 	if append {
-		flag = flag | os.O_APPEND
+		flag = os.O_RDWR | os.O_CREATE | os.O_APPEND
+	} else {
+		flag = os.O_RDWR | os.O_CREATE | os.O_TRUNC
 	}
 
 	f, err := os.OpenFile(filepath, flag, 0644)
diff --git a/fileutil/file_test.go b/fileutil/file_test.go
index b3f8b47..a4ae7a7 100644
--- a/fileutil/file_test.go
+++ b/fileutil/file_test.go
@@ -393,9 +393,7 @@ func TestWriteStringToFile(t *testing.T) {
 		t.Fail()
 	}
 
-	defer file.Close()
-
-	err = WriteStringToFile(filepath, "hello", false)
+	err = WriteStringToFile(filepath, "hello world", false)
 	if err != nil {
 		t.Fail()
 	}
@@ -405,20 +403,32 @@ func TestWriteStringToFile(t *testing.T) {
 		t.Fail()
 	}
 
+	err = WriteStringToFile(filepath, "hello", false)
+	if err != nil {
+		t.Fail()
+	}
+
+	content2, err := ReadFileToString(filepath)
+	if err != nil {
+		t.Fail()
+	}
+
 	err = WriteStringToFile(filepath, " world", true)
 	if err != nil {
 		t.Fail()
 	}
 
-	content2, err := os.ReadFile(filepath)
+	content3, err := os.ReadFile(filepath)
 	if err != nil {
 		t.Fail()
 	}
 
-	assert.Equal("hello", content1)
-	assert.Equal("hello world", string(content2))
+	assert.Equal("hello world", content1)
+	assert.Equal("hello", content2)
+	assert.Equal("hello world", string(content3))
 
-	os.Remove(filepath)
+	_ = file.Close()
+	_ = os.Remove(filepath)
 }
 
 func TestWriteBytesToFile(t *testing.T) {