diff --git a/extra/math/primes/twins/twins.factor b/extra/math/primes/twins/twins.factor
index 449dfadf6f..ba06ce9225 100644
--- a/extra/math/primes/twins/twins.factor
+++ b/extra/math/primes/twins/twins.factor
@@ -7,7 +7,7 @@ math.primes sequences ;
 IN: math.primes.twins
 
 : twin-primes-upto ( n -- seq )
-    primes-upto 2 <clumps> [ first2 - abs 2 = ] filter ;
+    primes-upto 2 clump [ first2 - abs 2 = ] filter ;
 
 : twin-primes? ( x y -- ? )
     { [ - abs 2 = ] [ nip prime? ] [ drop prime? ] } 2&& ;