diff --git a/src/documents/admin.py b/src/documents/admin.py
index 90d952fda..718901f47 100644
--- a/src/documents/admin.py
+++ b/src/documents/admin.py
@@ -71,12 +71,12 @@ class DocumentAdmin(CommonAdmin):
 
     def thumbnail(self, obj):
         if settings.FORCE_SCRIPT_NAME:
-            _src="{}/fetch/thumb/{}".format(settings.FORCE_SCRIPT_NAME,obj.id)
+            src_link = "{}/fetch/thumb/{}".format(settings.FORCE_SCRIPT_NAME, obj.id)
         else:
-            _src="/fetch/thumb/{}".format(obj.id)
+            src_link = "/fetch/thumb/{}".format(obj.id)
         png_img = self._html_tag(
             "img",
-            src=_src,
+            src=src_link,
             width=180,
             alt="Thumbnail of {}".format(obj.file_name),
             title=obj.file_name