diff --git a/parser/src/python.lalrpop b/parser/src/python.lalrpop
index aa15d5165..36900002f 100644
--- a/parser/src/python.lalrpop
+++ b/parser/src/python.lalrpop
@@ -340,7 +340,7 @@ TestList: Vec<ast::Expression> = {
 };
 
 FunctionArguments: Vec<ast::Expression> = {
-  <e: Comma<Expression>> => e,
+  <e: Comma<Test>> => e,
 };
 
 Comma<T>: Vec<T> = {