diff --git a/assemble.rkt b/assemble.rkt
index 910fa2b..03974dc 100644
--- a/assemble.rkt
+++ b/assemble.rkt
@@ -281,7 +281,7 @@ EOF
               [(boolean? val)
                (if val "true" "false")]
               [(empty? val)
-               (format "undefined")]
+               (format "Primitives.NULL")]
               [else
                (format "~s" val)])))
 
diff --git a/browser-evaluate.rkt b/browser-evaluate.rkt
index b7e6856..fa2c2de 100644
--- a/browser-evaluate.rkt
+++ b/browser-evaluate.rkt
@@ -210,7 +210,9 @@ function createXMLHTTPObject() {
 var comet = function() {
     sendRequest("/eval", 
                 function(req) {
-                    console.log(req.responseText);
+                    // debug:
+                    if (console && typeof(console.log) === 'function') { console.log(req.responseText); }
+
                     var invoke = eval(req.responseText)();
                     var output = [];
                     var startTime, endTime;
diff --git a/test-compiler.rkt b/test-compiler.rkt
index cc57c3f..248eece 100644
--- a/test-compiler.rkt
+++ b/test-compiler.rkt
@@ -462,10 +462,26 @@
 (test (begin (define (sum-integers a b)
                (if (> a b)
                    0
-                   (+ a (sum-integers (+ a 1) b))))
+                   (+ a (sum-integers (+ a 1) b))))        
              (sum-integers 1 100))
       (* 50 101))
 
 
+(test (begin (define (sum term a next b)
+               (if (> a b)
+                   0
+                   (+ (term a)
+                      (sum term (next a) next b))))
+             (define (inc n) (+ n 1))
+             (define (identity x) x)
+             (define (cube x) (* x x x))
+             (define (sum-cubes a b) (sum cube a inc b))
+             (define (sum-integers a b) (sum identity a inc b))
+             
+             (list (sum-cubes 1 10)
+                   (sum-integers 1 10)))
+      (list 3025 55))
+                     
+
 ;(simulate (compile (parse '42) 'val 'next))
 ;(compile (parse '(+ 3 4)) 'val 'next)
\ No newline at end of file