diff --git a/core/classes/mixin/mixin.factor b/core/classes/mixin/mixin.factor
index 56e995899b..d569103d97 100755
--- a/core/classes/mixin/mixin.factor
+++ b/core/classes/mixin/mixin.factor
@@ -62,10 +62,13 @@ TUPLE: check-mixin-class mixin ;
     ] if-mixin-member? ;
 
 : remove-mixin-instance ( class mixin -- )
+    #! The order of the three clauses is important here. The last
+    #! one must come after the other two so that the entries it
+    #! adds to changed-generics are not overwritten.
     [
-        [ class-usages update-methods ]
         [ [ swap remove ] change-mixin-class ]
         [ nip update-classes ]
+        [ class-usages update-methods ]
         2tri
     ] [ 2drop ] if-mixin-member? ;
 
diff --git a/core/compiler/units/units.factor b/core/compiler/units/units.factor
index fa29a5a519..cb361ec9e6 100755
--- a/core/compiler/units/units.factor
+++ b/core/compiler/units/units.factor
@@ -110,8 +110,7 @@ SYMBOL: update-tuples-hook
 : (compiled-generic-usages) ( generic class -- assoc )
     dup class? [
         [ compiled-generic-usage ] dip
-        [ [ classes-intersect? ] [ null class<= ] bi or nip ]
-        curry assoc-filter
+        [ classes-intersect? nip ] curry assoc-filter
     ] [ 2drop f ] if ;
 
 : compiled-generic-usages ( assoc -- assocs )