diff --git a/core/sets/sets.factor b/core/sets/sets.factor
index 904d0d95d7..06f6e04655 100644
--- a/core/sets/sets.factor
+++ b/core/sets/sets.factor
@@ -64,7 +64,7 @@ M: set subset?
     small/large sequence/tester all? ;
 
 M: set set=
-    2dup [ cardinality ] bi@ = [ subset? ] [ 2drop f ] if ;
+    2dup [ cardinality ] bi@ eq? [ subset? ] [ 2drop f ] if ;
 
 M: set fast-set ;