diff --git a/extra/sets/extras/extras-tests.factor b/extra/sets/extras/extras-tests.factor
index 9458f4aecd..a33d88d231 100644
--- a/extra/sets/extras/extras-tests.factor
+++ b/extra/sets/extras/extras-tests.factor
@@ -25,4 +25,4 @@ IN: sets.extras.tests
 
 { HS{ 0 10 20 30 40 } } [ 5 iota [ 10 * ] mapped-set ] unit-test
 
-{ { 1 2 4 } } [ { 1 2 3 4 5 } [ 2/ ] duplicates-by ] unit-test
+{ { 1 2 4 } } [ { 1 2 3 4 5 } [ 2/ ] unique-by ] unit-test
diff --git a/extra/sets/extras/extras.factor b/extra/sets/extras/extras.factor
index 5810cd3b17..542b5962a6 100644
--- a/extra/sets/extras/extras.factor
+++ b/extra/sets/extras/extras.factor
@@ -35,5 +35,5 @@ IN: sets.extras
         '[ @ _ adjoin ] each
     ] keep ; inline
 
-: duplicates-by ( seq quot: ( elt -- key ) -- seq' )
+: unique-by ( seq quot: ( elt -- key ) -- seq' )
     over length <hash-set> '[ @ _ ?adjoin ] filter ; inline