diff --git a/vyper/ast/nodes.py b/vyper/ast/nodes.py
index 2497928035..69bd1fed53 100644
--- a/vyper/ast/nodes.py
+++ b/vyper/ast/nodes.py
@@ -1254,7 +1254,7 @@ def _op(self, left, right):
 
 
 class Call(ExprNode):
-    __slots__ = ("func", "args", "keywords", "keyword")
+    __slots__ = ("func", "args", "keywords")
 
 
 class keyword(VyperNode):