diff --git a/src/Symfony/Component/HttpFoundation/File/MimeType/FileinfoMimeTypeGuesser.php b/src/Symfony/Component/HttpFoundation/File/MimeType/FileinfoMimeTypeGuesser.php
index fc4bc45024..fa4c962d7d 100644
--- a/src/Symfony/Component/HttpFoundation/File/MimeType/FileinfoMimeTypeGuesser.php
+++ b/src/Symfony/Component/HttpFoundation/File/MimeType/FileinfoMimeTypeGuesser.php
@@ -63,7 +63,13 @@ class FileinfoMimeTypeGuesser implements MimeTypeGuesserInterface
         if (!$finfo = new \finfo(FILEINFO_MIME_TYPE, $this->magicFile)) {
             return null;
         }
+        $mimeType = $finfo->file($path);
 
-        return $finfo->file($path);
+        if ($mimeType && 0 === (\strlen($mimeType) % 2)) {
+            $mimeStart = substr($mimeType, 0, \strlen($mimeType) >> 1);
+            $mimeType = $mimeStart.$mimeStart === $mimeType ? $mimeStart : $mimeType;
+        }
+
+        return $mimeType;
     }
 }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/File/Fixtures/test.docx b/src/Symfony/Component/HttpFoundation/Tests/File/Fixtures/test.docx
new file mode 100644
index 0000000000..2e86b6fcea
Binary files /dev/null and b/src/Symfony/Component/HttpFoundation/Tests/File/Fixtures/test.docx differ
diff --git a/src/Symfony/Component/HttpFoundation/Tests/File/MimeType/MimeTypeTest.php b/src/Symfony/Component/HttpFoundation/Tests/File/MimeType/MimeTypeTest.php
index 0418726b5b..e38816687f 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/File/MimeType/MimeTypeTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/File/MimeType/MimeTypeTest.php
@@ -60,6 +60,14 @@ class MimeTypeTest extends TestCase
         $this->assertEquals('application/octet-stream', MimeTypeGuesser::getInstance()->guess(__DIR__.'/../Fixtures/.unknownextension'));
     }
 
+    /**
+     * @requires PHP 7.0
+     */
+    public function testGuessWithDuplicatedFileType()
+    {
+        $this->assertEquals('application/vnd.openxmlformats-officedocument.wordprocessingml.document', MimeTypeGuesser::getInstance()->guess(__DIR__.'/../Fixtures/test.docx'));
+    }
+
     public function testGuessWithIncorrectPath()
     {
         $this->expectException('Symfony\Component\HttpFoundation\File\Exception\FileNotFoundException');