Remove unused parameter
diff --git a/Lib/fontTools/ttLib/tables/otBase.py b/Lib/fontTools/ttLib/tables/otBase.py
index aba9866..8f06e40 100644
--- a/Lib/fontTools/ttLib/tables/otBase.py
+++ b/Lib/fontTools/ttLib/tables/otBase.py
@@ -101,7 +101,7 @@
 		self.valueFormat = valueFormat
 		self.cachingStats = cachingStats
 
-	def getSubReader(self, offset, persistent=False):
+	def getSubReader(self, offset):
 		offset = self.offset + offset
 		if self.cachingStats is not None:
 			try: