diff --git a/src/Lexer.hs b/src/Lexer.hs
index 5ee1423..f5bdbea 100644
--- a/src/Lexer.hs
+++ b/src/Lexer.hs
@@ -25,8 +25,8 @@ keywordT = string "t" *> notFollowedBy alphaNumChar *> pure LKeywordT
 identifier :: Lexer LToken
 identifier = do
   name <- some (letterChar <|> char '_' <|> char '-')
-  if name == "t"
-    then fail "Keyword 't' cannot be used as an identifier"
+  if (name == "t" || name == "__result")
+    then fail "Keywords (`t`, `__result`) cannot be used as an identifier"
     else return (LIdentifier name)
 
 integerLiteral :: Lexer LToken