diff --git a/TODO.FACTOR.txt b/TODO.FACTOR.txt
index b6cacd1dd5..7202a609b6 100644
--- a/TODO.FACTOR.txt
+++ b/TODO.FACTOR.txt
@@ -38,6 +38,7 @@
 - FactorLib.equal() not very good
 - do nset-nth, nremove-nth, nsubstitute, ninject
 - IN: format base: work with all types of numbers
+- investigate mandel.factor
 
 + listener/plugin:
 
diff --git a/contrib/mandel.factor b/contrib/mandel.factor
index 7db6c076d8..fa48a2c7e8 100644
--- a/contrib/mandel.factor
+++ b/contrib/mandel.factor
@@ -13,7 +13,6 @@
 !                (princ (code-char c))))
 !        (format t "~%"))
 
-USE: arithmetic
 USE: combinators
 USE: math
 USE: prettyprint
@@ -28,14 +27,14 @@ USE: strings
         r> f
     ] ifte ;
 
-: mandel-step ( a z c -- c )
-    [ ?mandel-step ] [ ] while nip nip ;
+: mandel-step ( a z c -- )
+    [ ?mandel-step ] [ ] while >char write 2drop ;
 
 : mandel-x ( x y -- )
-    rect> dup CHAR: ~ mandel-step >char write ;
+    rect> dup CHAR: ~ mandel-step ;
 
 : mandel-y ( y -- )
-    75 [ dupd 25 / 2 - swap mandel-x ] times* drop terpri ;
+    75 [ dupd 25 / 2 - >float swap mandel-x ] times* drop ;
 
 : mandel ( -- )
-    21 [ 10 / 1 - mandel-y ] times* ;
+    21 [ 10 / 1 - >float mandel-y terpri ] times* ;