diff --git a/extra/math/extras/extras.factor b/extra/math/extras/extras.factor
index 02a75982fc..f0a35e7ee4 100644
--- a/extra/math/extras/extras.factor
+++ b/extra/math/extras/extras.factor
@@ -99,7 +99,7 @@ PRIVATE>
     [ 1 ] 2dip '[ dupd swap - _ * + dup ] map nip ;
 
 : moving-median ( u n -- v )
-    <clumps> [ median ] map ;
+    clump [ median ] map ;
 
 : moving-supremum ( u n -- v )
     <clumps> [ supremum ] map ;