diff --git a/youtube_dlc/postprocessor/embedthumbnail.py b/youtube_dlc/postprocessor/embedthumbnail.py
index 7ca0ce6e5..e9f2161a0 100644
--- a/youtube_dlc/postprocessor/embedthumbnail.py
+++ b/youtube_dlc/postprocessor/embedthumbnail.py
@@ -89,9 +89,11 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
             os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
         elif info['ext'] == 'mkv':
-            os.rename(encodeFilename(thumbnail_filename), encodeFilename('cover.jpg'))
             old_thumbnail_filename = thumbnail_filename
-            thumbnail_filename = 'cover.jpg'
+            thumbnail_filename = os.path.join(os.path.dirname(old_thumbnail_filename), 'cover.jpg')
+            if os.path.exists(thumbnail_filename):
+                os.remove(encodeFilename(thumbnail_filename))
+            os.rename(encodeFilename(old_thumbnail_filename), encodeFilename(thumbnail_filename))
 
             options = [
                 '-c', 'copy', '-map', '0',