diff --git a/runtime.js b/runtime.js
index 474133d..12c3c02 100644
--- a/runtime.js
+++ b/runtime.js
@@ -129,6 +129,11 @@ var Primitives = (function() {
 	    var firstArg = MACHINE.env[MACHINE.env.length-1];
 	    return firstArg[1];
 	},
+	
+	'not': function(arity, returnLabel) {
+	    var firstArg = MACHINE.env[MACHINE.env.length-1];
+	    return (!firstArg);
+	},
 
 	'null' : NULL,
 
@@ -150,7 +155,11 @@ var Primitives = (function() {
  	'call/cc': new Closure(callCCEntry,
  			       1,
  			       [],
- 			       "call/cc")
+ 			       "call/cc"),
+	'call-with-current-continuation': new Closure(callCCEntry,
+ 						      1,
+ 						      [],
+ 						      "call-with-current-continuation")
 
     };
 })();
diff --git a/simulator-primitives.rkt b/simulator-primitives.rkt
index 51d3e46..5f60338 100644
--- a/simulator-primitives.rkt
+++ b/simulator-primitives.rkt
@@ -33,9 +33,12 @@
   (make-closure call/cc-label
                 1
                 '()))
+(define call-with-current-continuation call/cc)
 
 (define e (exp 1))
 
+
+
 (define lookup-primitive (make-lookup #:functions (+ - * / = < <= > >= cons list car cdr
                                                      sub1
                                                      display newline displayln
@@ -52,4 +55,4 @@
                                                      display
                                                      displayln
                                                      newline)
-                                      #:constants (null pi e call/cc)))
+                                      #:constants (null pi e call/cc call-with-current-continuation)))
diff --git a/test-browser-evaluate.rkt b/test-browser-evaluate.rkt
index ee9f597..cf866e3 100644
--- a/test-browser-evaluate.rkt
+++ b/test-browser-evaluate.rkt
@@ -93,3 +93,35 @@
               )
       "32")
 
+(test  '(begin
+          (define (ctak x y z)
+            (call-with-current-continuation
+             (lambda (k)
+               (ctak-aux k x y z))))
+          
+          (define (ctak-aux k x y z)
+            (cond ((not (< y x))  ;xy
+                   (k z))
+                  (else (call-with-current-continuation
+                         (ctak-aux
+                          k
+                          (call-with-current-continuation
+                           (lambda (k)
+                             (ctak-aux k
+                                       (- x 1)
+                                       y
+                                       z)))
+                          (call-with-current-continuation
+                           (lambda (k)
+                             (ctak-aux k
+                                       (- y 1)
+                                       z
+                                       x)))
+                          (call-with-current-continuation
+                           (lambda (k)
+                             (ctak-aux k
+                                       (- z 1)
+                                       x
+                                       y))))))))
+          (displayln (ctak 18 12 6)))
+       "7\n")
diff --git a/test-compiler.rkt b/test-compiler.rkt
index 7f73fc5..17721c2 100644
--- a/test-compiler.rkt
+++ b/test-compiler.rkt
@@ -561,5 +561,47 @@
       (error "puzzle failed: ~s" (get-output-string op)))))
                 
 
+
+
+;; ctak
+(test (begin
+        (define (ctak x y z)
+          (call-with-current-continuation
+           (lambda (k)
+             (ctak-aux k x y z))))
+        
+        (define (ctak-aux k x y z)
+          (cond ((not (< y x))  ;xy
+                 (k z))
+                (else (call-with-current-continuation
+                       (ctak-aux
+                        k
+                        (call-with-current-continuation
+                         (lambda (k)
+                           (ctak-aux k
+                                     (- x 1)
+                                     y
+                                     z)))
+                        (call-with-current-continuation
+                         (lambda (k)
+                           (ctak-aux k
+                                     (- y 1)
+                                     z
+                                     x)))
+                        (call-with-current-continuation
+                         (lambda (k)
+                           (ctak-aux k
+                                     (- z 1)
+                                     x
+                                     y))))))))
+        (ctak 18 12 6))
+      7)
+
+
+
+
+
+
+
 ;(simulate (compile (parse '42) 'val 'next))
 ;(compile (parse '(+ 3 4)) 'val 'next)
\ No newline at end of file