diff --git a/tools/cc.ebnf b/tools/cc.ebnf
index 6e6b7bb..f48a3f4 100644
--- a/tools/cc.ebnf
+++ b/tools/cc.ebnf
@@ -92,7 +92,7 @@ initializer_list: "{" [init_list_field ("," init_list_field)* ","? ] "}"
            | prec5_expr ">>" prec4_expr    -> shr
 ?prec4_expr: prec3_expr
            | prec4_expr "+" prec3_expr     -> add
-           | prec4_expr "-" prec3_expr     -> su
+           | prec4_expr "-" prec3_expr     -> sub
 ?prec3_expr: prec2_expr
            | prec3_expr "*" prec2_expr     -> mul
            | prec3_expr "/" prec2_expr     -> div