diff --git a/grammars/builtins.bp b/grammars/builtins.bp
index 888cc2c..8b405b0 100644
--- a/grammars/builtins.bp
+++ b/grammars/builtins.bp
@@ -19,7 +19,7 @@ string: `" ..%string-escape `" / `' ..%string-escape `'
 string-escape: `\ (`x 2 Hex / 1-3 `0-7 / `u 1-4 Hex / .)
 left-id-edge: !<id-char
 right-id-edge: !id-char
-id: left-id-edge !`0-9 !(keyword left-id-edge) +id-char
+id: left-id-edge !`0-9 !(keyword !id-char) +id-char
 id-char: `a-z,A-Z,_,0-9
 var: id
 keyword: !"" # No keywords defined by default