Index: generic/nsf.c
===================================================================
diff -u -rd1d314bac8a9baa0268fc673623432290adb08b7 -rb4266efa283e86989f6f09f3938f41f173580400
--- generic/nsf.c	(.../nsf.c)	(revision d1d314bac8a9baa0268fc673623432290adb08b7)
+++ generic/nsf.c	(.../nsf.c)	(revision b4266efa283e86989f6f09f3938f41f173580400)
@@ -7760,7 +7760,6 @@
   NsfClasses *filterCheck, *osl = NULL;
   NsfObjectSystem *osPtr;
   NsfClass **scl;
-  int reversed = 0;
   int i, j;
 
   filterCheck = ComputeOrder(cl, SUPER_CLASSES);
@@ -7778,8 +7777,10 @@
     FilterRemoveDependentFilterCmds(cl, filterCheck->cl);
   }
 
-  /* invalidate all interceptors orders of instances of this
-     and of all depended classes */
+  /* 
+   * Invalidate all interceptors orders of instances of this and of all
+   * depended classes.
+   */
   MixinInvalidateObjOrders(interp, cl);
   FilterInvalidateObjOrders(interp, cl);
 
@@ -7792,23 +7793,19 @@
   }
 
   /*
-   * check that superclasses don't precede their classes
+   * Check that superclasses don't precede their classes.
    */
-
   for (i = 0; i < oc; i++) {
-    if (reversed) break;
     for (j = i+1; j < oc; j++) {
       NsfClasses *dl = ComputeOrder(scl[j], SUPER_CLASSES);
-      if (reversed) break;
       dl = NsfClassListFind(dl, scl[i]);
-      if (dl) reversed = 1;
+      if (dl) {
+	FREE(NsfClass**, scl);
+	return NsfObjErrType(interp, "superclass", arg, "classes in dependence order", NULL);
+      }
     }
   }
 
-  if (reversed) {
-    return NsfObjErrType(interp, "superclass", arg, "classes in dependence order", NULL);
-  }
-
   /*
    * Ensure that the current class and new superclasses are from the
    * same object system.
@@ -7817,7 +7814,7 @@
   for (i = 0; i < oc; i++) {
     if (osPtr != GetObjectSystem(&scl[i]->object)) {
       FREE(NsfClass**, scl);
-      return NsfPrintError(interp, "class \"%s\" has different object system as class  \"%s\"",
+      return NsfPrintError(interp, "class \"%s\" has a different object system as class  \"%s\"",
 			   ClassName(cl), ClassName(scl[i]));
     }
   }
Index: tests/contains.test
===================================================================
diff -u -ra24e1f836c3126d0a0e9467bde3a9fa8da901711 -rb4266efa283e86989f6f09f3938f41f173580400
--- tests/contains.test	(.../contains.test)	(revision a24e1f836c3126d0a0e9467bde3a9fa8da901711)
+++ tests/contains.test	(.../contains.test)	(revision b4266efa283e86989f6f09f3938f41f173580400)
@@ -3,7 +3,7 @@
 
 #
 # Intentionally, we do not want to make a "namespace import" in this
-# test file.
+# test file. Run this file via a pure tclsh!
 #
 namespace path nx
 
@@ -105,19 +105,20 @@
 package require XOTcl
 
 ########################################################################
+# trigger the call of "cleanup" to work via method dispatch
+::xotcl::Object create o1
+o1 proc cleanup {} {return}
+
+########################################################################
 #
 # Test that we do not allow to mix object systems within the intrinsic
 # classes of an object. Otherwise we would have problems with the
 # recreate "C0 create c0". On a recreate of c0 the object system for
 # C0 is ::xotcl, therefore we try to call recreate. In the C0 class
 # hierarchy is from nx and contains no "recreate" method.
 
-# trigger the call of "cleanup" to work via method dispatch
-::xotcl::Object create o1
-o1 proc cleanup {} {return}
-
 ? {catch {::xotcl::Class create C0 -superclass ::nx::Object} errorMsg} 1
-? {set ::errorMsg} {class "::C0" has different object system as class  "::nx::Object"}
+? {set ::errorMsg} {class "::C0" has a different object system as class  "::nx::Object"}
 ::nx::Class create C1 -superclass ::nx::Object
 
 #C0 create c0