diff --git a/basis/math/functions/functions.factor b/basis/math/functions/functions.factor
index c21586f9cc..b94effa297 100644
--- a/basis/math/functions/functions.factor
+++ b/basis/math/functions/functions.factor
@@ -8,7 +8,7 @@ IN: math.functions
     [ numerator ] [ denominator ] bi ; inline
 
 : rect> ( x y -- z )
-    dup 0 = [ drop ] [ complex boa ] if ; inline
+    [ complex boa ] unless-zero ; inline
 
 GENERIC: sqrt ( x -- y ) foldable