1 files changed, 1 insertions, 0 deletions

diff --git a/src/parser.c b/src/parser.c
index 57efd96..86cf713 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -9,6 +9,7 @@ static char *builtins [] = {
     "+", "-", "*", "/", "%",
     "=", "<", ">", "<=", ">=",
     "not", "and", "or",
+    "nil?", "zero?", "fixnum?", "bool?",
 };
 
 uint64_t