diff --git a/extra/math/extras/extras.factor b/extra/math/extras/extras.factor
index bdc92c300b..9ba914930f 100644
--- a/extra/math/extras/extras.factor
+++ b/extra/math/extras/extras.factor
@@ -155,7 +155,7 @@ PRIVATE>
 : until-zero ( n quot -- )
     [ dup zero? ] swap until drop ; inline
 
-: cum-reduce ( ... seq identity quot: ( ... prev elt -- ... next ) -- ... result cum-result )
+: cum-reduce ( seq identity quot: ( prev elt -- next ) -- result cum-result )
     [ dup rot ] dip dup '[ _ curry dip dupd @ ] each ; inline
 
 <PRIVATE