diff --git a/basis/summary/summary.factor b/basis/summary/summary.factor
index 89f4a61af6..fb46d3f11b 100644
--- a/basis/summary/summary.factor
+++ b/basis/summary/summary.factor
@@ -1,13 +1,12 @@
 ! Copyright (C) 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors assocs classes continuations kernel make math
-math.parser sequences ;
+math.parser sequences sets ;
 IN: summary
 
 GENERIC: summary ( object -- string )
 
-: object-summary ( object -- string )
-    class-of name>> ; inline
+: object-summary ( object -- string ) class-of name>> ; inline
 
 M: object summary object-summary ;
 
@@ -27,6 +26,14 @@ M: assoc summary
         " entries" %
     ] "" make ;
 
+M: set summary
+    [
+        dup class-of name>> %
+        " with " %
+        cardinality #
+        " members" %
+    ] "" make ;
+
 ! Override sequence => integer instance
 M: f summary object-summary ;