diff --git a/src/LispFactory.php b/src/LispFactory.php
index f826f13..5969d25 100644
--- a/src/LispFactory.php
+++ b/src/LispFactory.php
@@ -55,6 +55,9 @@ class LispFactory
         $lisp->readEval('(def defn (macro (name args body) (quasiquote (def (unquote name) (fn (unquote args) (unquote body))))))');
         $lisp->readEval('(def defmacro (macro (name args body) (quasiquote (def (unquote name) (macro (unquote args) (unquote body))))))');
 
+        $lisp->readEval('(def when (macro (test body) (quasiquote (if (unquote test) (unquote body) null))))');
+        $lisp->readEval('(def unless (macro (test body) (quasiquote (if (unquote test) null (unquote body)))))');
+
         // Separate environment for user-defined stuff
         $lisp->setEnv(new Env('user', $env));