Minor
diff --git a/Lib/fontTools/merge.py b/Lib/fontTools/merge.py
index c0a5ace..7606d10 100644
--- a/Lib/fontTools/merge.py
+++ b/Lib/fontTools/merge.py
@@ -22,8 +22,7 @@
 	allowDefault = kwargs.get('allowDefaultTable', False)
 	def wrapper(method):
 		for clazz in clazzes:
-			if not allowDefault:
-				assert clazz != DefaultTable, 'Oops, table class not found.'
+			assert allowDefault or clazz != DefaultTable, 'Oops, table class not found.'
 			assert method.__name__ not in clazz.__dict__, \
 				"Oops, class '%s' has method '%s'." % (clazz.__name__,
 								       method.__name__)