diff --git a/libs/subzero/modification/main.py b/libs/subzero/modification/main.py
index 884c90de6..68ba77838 100644
--- a/libs/subzero/modification/main.py
+++ b/libs/subzero/modification/main.py
@@ -22,6 +22,7 @@ class SubtitleModifications(object):
     language = None
     initialized_mods = {}
     mods_used = []
+    only_uppercase = False
     f = None
 
     font_style_tag_start = u"{\\"