diff --git a/src/language/PEGGrammar.hpp b/src/language/PEGGrammar.hpp
index 2a8ea0374deeb1f334e3a533609e278df76d33a7..00e21818ed543112405b7cb07eed4d155b5f5c4d 100644
--- a/src/language/PEGGrammar.hpp
+++ b/src/language/PEGGrammar.hpp
@@ -146,7 +146,8 @@ struct close_parent : seq< one< ')' >, ignored > {};
 struct expression;
 struct parented_expression : if_must< open_parent, expression, close_parent >{};
 
-struct function_argument_list : if_must< open_parent, list_must< expression, COMMA >, close_parent >{};
+struct tuple_expression;
+struct function_argument_list : if_must< open_parent, list_must< sor< tuple_expression, expression >, COMMA >, close_parent >{};
 struct function_evaluation : seq< NAME, function_argument_list > {};
 
 struct primary_expression : sor< BOOL, REAL, INTEGER, LITERAL, function_evaluation, NAME, parented_expression > {};