diff --git a/src/language/PEGGrammar.hpp b/src/language/PEGGrammar.hpp
index 3dac6bd40cee2b61b3300583fb77f44ba872b6d5..b1b38caed0d1ada4133b6b14c6648864e2ef65f7 100644
--- a/src/language/PEGGrammar.hpp
+++ b/src/language/PEGGrammar.hpp
@@ -128,7 +128,7 @@ struct unary_minusminus : TAO_PEGTL_STRING("--") {};
 struct unary_plus :  one< '+' > {};
 struct unary_minus : one< '-' > {};
 
-struct unary_not : sor< one< '!'> , not_kw > {};
+struct unary_not : not_kw {};
 
 struct unary_operator : seq< sor< unary_plusplus, unary_minusminus, unary_plus, unary_minus, unary_not>, ignored > {};