diff --git a/classes/controller.php b/classes/controller.php
index 0c9b5548..cbe02428 100644
--- a/classes/controller.php
+++ b/classes/controller.php
@@ -2361,21 +2361,9 @@ class AdminController
 
         $file = $obj->file();
         if ($file) {
-            $filename = substr($obj->name(), 0, -(strlen('.' . $language . '.md')));
+            $filename = $this->determineFilenameIncludingLanguage($obj->name(), $language);
 
-            if (substr($filename, -3, 1) == '.') {
-                if (substr($filename, -2) == substr($language, 0, 2)) {
-                    $filename = str_replace(substr($filename, -2), $language, $filename);
-                }
-            } elseif (substr($filename, -6, 1) == '.') {
-                if (substr($filename, -5) == substr($language, 0, 5)) {
-                    $filename = str_replace(substr($filename, -5), $language, $filename);
-                }
-            } else {
-                $filename .= '.' . $language;
-            }
-
-            $path = $obj->path() . DS . $filename . '.md';
+            $path = $obj->path() . DS . $filename;
             $aFile = File::instance($path);
             $aFile->save();
 
@@ -2394,6 +2382,29 @@ class AdminController
         return true;
     }
 
+    /**
+     * The what should be the new filename when saving as a new language
+     *
+     * @param string $current_filename the current file name, including .md. Example: default.en.md
+     * @param string $language The new language it will be saved as. Example: 'it' or 'en-GB'.
+     *
+     * @return string The new filename. Example: 'default.it'
+     */
+    public function determineFilenameIncludingLanguage($current_filename, $language)
+    {
+        $filename = substr($current_filename, 0, -(strlen('.md')));
+
+        if (substr($filename, -3, 1) == '.') {
+            $filename = str_replace(substr($filename, -2), $language, $filename);
+        } elseif (substr($filename, -6, 1) == '.') {
+            $filename = str_replace(substr($filename, -5), $language, $filename);
+        } else {
+            $filename .= '.' . $language;
+        }
+
+        return $filename . '.md';
+    }
+
     /**
      * Determine if the user can edit media
      *
diff --git a/tests/unit/classes/controllerTest.php b/tests/unit/classes/controllerTest.php
new file mode 100644
index 00000000..329768ba
--- /dev/null
+++ b/tests/unit/classes/controllerTest.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace Grav\Plugin;
+
+/**
+ * Class ControllerTest
+ */
+class ControllerTest extends \Codeception\TestCase\Test
+{
+    protected $controller;
+
+
+    protected function _before()
+    {
+        require_once(__DIR__ . '/../../../classes/controller.php');
+        $this->controller = new AdminController();
+    }
+
+    protected function _after()
+    {
+
+    }
+
+    public function testDetermineFilenameIncludingLanguage()
+    {
+        $language = 'en-GB';
+
+        $this->assertSame('testing.en-GB.md', $this->controller->determineFilenameIncludingLanguage('testing.md', $language));
+        $this->assertSame('testing.en-GB.md', $this->controller->determineFilenameIncludingLanguage('testing.en.md', $language));
+        $this->assertSame('testing.en-GB.md', $this->controller->determineFilenameIncludingLanguage('testing.it.md', $language));
+        $this->assertSame('testing.en-GB.md', $this->controller->determineFilenameIncludingLanguage('testing.en-GB.md', $language));
+
+        $language = 'it';
+
+        $this->assertSame('testing.it.md', $this->controller->determineFilenameIncludingLanguage('testing.md', $language));
+        $this->assertSame('testing.it.md', $this->controller->determineFilenameIncludingLanguage('testing.en.md', $language));
+        $this->assertSame('testing.it.md', $this->controller->determineFilenameIncludingLanguage('testing.it.md', $language));
+        $this->assertSame('testing.it.md', $this->controller->determineFilenameIncludingLanguage('testing.en-GB.md', $language));
+    }
+}
+