diff --git a/Lib/fontTools/misc/psCharStrings.py b/Lib/fontTools/misc/psCharStrings.py
index ccb7e1cff..9b2105bb0 100644
--- a/Lib/fontTools/misc/psCharStrings.py
+++ b/Lib/fontTools/misc/psCharStrings.py
@@ -242,7 +242,7 @@ class T2CharString(ByteCodeBase):
 		self.bytecode = bytecode
 		self.program = program
 		self.private = private
-		self.globalSubrs = globalSubrs
+		self.globalSubrs = globalSubrs if globalSubrs is not None else []
 	
 	def __repr__(self):
 		if self.bytecode is None: