diff --git a/basis/compiler/compiler.factor b/basis/compiler/compiler.factor
index a78c6f729a..94b927ca82 100644
--- a/basis/compiler/compiler.factor
+++ b/basis/compiler/compiler.factor
@@ -184,8 +184,8 @@ M: optimizing-compiler update-call-sites ( class generic -- words )
     #! Words containing call sites with inferred type 'class'
     #! which inlined a method on 'generic'
     compiled-generic-usage swap '[
-        nip dup forgotten-class?
-        [ drop f ] [ _ classes-intersect? ] if
+        nip dup classoid?
+        [ _ classes-intersect? ] [ drop f ] if
     ] assoc-filter keys ;
 
 M: optimizing-compiler recompile ( words -- alist )
diff --git a/basis/stack-checker/dependencies/dependencies.factor b/basis/stack-checker/dependencies/dependencies.factor
index 6fa2ae4eab..d995354a52 100644
--- a/basis/stack-checker/dependencies/dependencies.factor
+++ b/basis/stack-checker/dependencies/dependencies.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2009, 2010 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: assocs accessors classes.algebra fry generic kernel math
-namespaces sequences words sets ;
+namespaces sequences words sets combinators.short-circuit ;
 FROM: classes.tuple.private => tuple-layout ;
 IN: stack-checker.dependencies
 
@@ -62,7 +62,11 @@ TUPLE: depends-on-class<= class1 class2 ;
     \ depends-on-class<= add-conditional-dependency ;
 
 M: depends-on-class<= satisfied?
-    [ class1>> ] [ class2>> ] bi class<= ;
+    {
+        [ class1>> classoid? ]
+        [ class2>> classoid? ]
+        [ [ class1>> ] [ class2>> ] bi class<= ]
+    } 1&& ;
 
 TUPLE: depends-on-classes-disjoint class1 class2 ;
 
@@ -70,7 +74,11 @@ TUPLE: depends-on-classes-disjoint class1 class2 ;
     \ depends-on-classes-disjoint add-conditional-dependency ;
 
 M: depends-on-classes-disjoint satisfied?
-    [ class1>> ] [ class2>> ] bi classes-intersect? not ;
+    {
+        [ class1>> classoid? ]
+        [ class2>> classoid? ]
+        [ [ class1>> ] [ class2>> ] bi classes-intersect? not ]
+    } 1&& ;
 
 TUPLE: depends-on-next-method class generic next-method ;
 
@@ -79,7 +87,10 @@ TUPLE: depends-on-next-method class generic next-method ;
     \ depends-on-next-method add-conditional-dependency ;
 
 M: depends-on-next-method satisfied?
-    [ [ class>> ] [ generic>> ] bi next-method ] [ next-method>> ] bi eq? ;
+    {
+        [ class>> classoid? ]
+        [ [ [ class>> ] [ generic>> ] bi next-method ] [ next-method>> ] bi eq? ]
+    } 1&& ;
 
 TUPLE: depends-on-method class generic method ;
 
@@ -88,7 +99,10 @@ TUPLE: depends-on-method class generic method ;
     \ depends-on-method add-conditional-dependency ;
 
 M: depends-on-method satisfied?
-    [ [ class>> ] [ generic>> ] bi method-for-class ] [ method>> ] bi eq? ;
+    {
+        [ class>> classoid? ]
+        [ [ [ class>> ] [ generic>> ] bi method-for-class ] [ method>> ] bi eq? ]
+    } 1&& ;
 
 TUPLE: depends-on-tuple-layout class layout ;
 
diff --git a/core/classes/algebra/algebra.factor b/core/classes/algebra/algebra.factor
index fe02e6b583..dc9226d20d 100644
--- a/core/classes/algebra/algebra.factor
+++ b/core/classes/algebra/algebra.factor
@@ -40,12 +40,12 @@ M: object normalize-class ;
 
 PRIVATE>
 
-GENERIC: forgotten-class? ( obj -- ? )
+GENERIC: classoid? ( obj -- ? )
 
-M: word forgotten-class? "forgotten" word-prop ;
-M: anonymous-union forgotten-class? members>> [ forgotten-class? ] any? ;
-M: anonymous-intersection forgotten-class? participants>> [ forgotten-class? ] any? ;
-M: anonymous-complement forgotten-class? class>> forgotten-class? ;
+M: word classoid? class? ;
+M: anonymous-union classoid? members>> [ classoid? ] all? ;
+M: anonymous-intersection classoid? participants>> [ classoid? ] all? ;
+M: anonymous-complement classoid? class>> classoid? ;
 
 : class<= ( first second -- ? )
     class<=-cache get [ (class<=) ] 2cache ;