diff --git a/parsecsv.lib.php b/parsecsv.lib.php
index 790df4a..7c9012d 100644
--- a/parsecsv.lib.php
+++ b/parsecsv.lib.php
@@ -418,7 +418,7 @@ class parseCSV {
             $file = &$this->file;
         }
 
-        $mode = $append ? 'at' : 'wt';
+        $mode = $append ? 'ab' : 'wb';
         $is_php = preg_match('/\.php$/i', $file) ? true : false;
 
         return $this->_wfile($file, $this->unparse($data, $fields, $append, $is_php), $mode);
diff --git a/tests/methods/SaveTest.php b/tests/methods/SaveTest.php
index d871975..4780b87 100644
--- a/tests/methods/SaveTest.php
+++ b/tests/methods/SaveTest.php
@@ -32,6 +32,18 @@ class SaveTest extends PHPUnit\Framework\TestCase {
         $this->saveAndCompare($expected);
     }
 
+    public function testSaveWithDosLineEnding() {
+        $this->csv->linefeed = "\r\n";
+        $expected = "SMS\r\n0444\r\n5555\r\n";
+        $this->saveAndCompare($expected);
+    }
+
+    public function testSaveWithUnixLineEnding() {
+        $this->csv->linefeed = "\n";
+        $expected = "SMS\n0444\n5555\n";
+        $this->saveAndCompare($expected);
+    }
+
     public function testAllQuotes() {
         $this->csv->enclose_all = true;
         $expected = "\"SMS\"\r\"0444\"\r\"5555\"\r";