diff --git a/core/classes/algebra/algebra.factor b/core/classes/algebra/algebra.factor
index b32bac3a18..51dad033a9 100644
--- a/core/classes/algebra/algebra.factor
+++ b/core/classes/algebra/algebra.factor
@@ -55,7 +55,7 @@ DEFER: (class-or)
     class-or-cache get [ (class-or) ] 2cache ;
 
 : superclass<= ( first second -- ? )
-    >r superclass r> class<= ;
+    swap superclass dup [ swap class<= ] [ 2drop f ] if ;
 
 : left-anonymous-union<= ( first second -- ? )
     >r members>> r> [ class<= ] curry all? ;
@@ -103,19 +103,20 @@ PREDICATE: empty-intersection < anonymous-intersection participants>> empty? ;
 
 : (class<=) ( first second -- -1/0/1 )
     2dup eq? [ 2drop t ] [
-        [ normalize-class ] bi@ {
-            { [ dup empty-intersection? ] [ 2drop t ] }
-            { [ over empty-union? ] [ 2drop t ] }
-            { [ 2dup [ anonymous-complement? ] both? ] [ anonymous-complement<= ] }
-            { [ over anonymous-union? ] [ left-anonymous-union<= ] }
-            { [ over anonymous-intersection? ] [ left-anonymous-intersection<= ] }
-            { [ over nontrivial-anonymous-complement? ] [ left-anonymous-complement<= ] }
-            { [ dup anonymous-union? ] [ right-anonymous-union<= ] }
-            { [ dup anonymous-intersection? ] [ right-anonymous-intersection<= ] }
-            { [ dup anonymous-complement? ] [ class>> classes-intersect? not ] }
-            { [ over superclass ] [ superclass<= ] }
-            [ 2drop f ]
-        } cond
+        2dup superclass<= [ 2drop t ] [
+            [ normalize-class ] bi@ {
+                { [ dup empty-intersection? ] [ 2drop t ] }
+                { [ over empty-union? ] [ 2drop t ] }
+                { [ 2dup [ anonymous-complement? ] both? ] [ anonymous-complement<= ] }
+                { [ over anonymous-union? ] [ left-anonymous-union<= ] }
+                { [ over anonymous-intersection? ] [ left-anonymous-intersection<= ] }
+                { [ over nontrivial-anonymous-complement? ] [ left-anonymous-complement<= ] }
+                { [ dup anonymous-union? ] [ right-anonymous-union<= ] }
+                { [ dup anonymous-intersection? ] [ right-anonymous-intersection<= ] }
+                { [ dup anonymous-complement? ] [ class>> classes-intersect? not ] }
+                [ 2drop f ]
+            } cond
+        ] if
     ] if ;
 
 M: anonymous-union (classes-intersect?)