diff --git a/parser.py b/parser.py
index b1fdc23..e08b1f2 100644
--- a/parser.py
+++ b/parser.py
@@ -442,7 +442,7 @@ class LLVMParser(object):
 
     def p_operand_null(self, p):
         'operand : NULL'
-        p[0] = ll.Null
+        p[0] = ll.Null()
 
     def p_operand_const(self, p):
         'operand : INT'