diff --git a/moo/kernel/X11.moo b/moo/kernel/X11.moo
index 8f4c59f..22638b7 100644
--- a/moo/kernel/X11.moo
+++ b/moo/kernel/X11.moo
@@ -16,6 +16,16 @@ interface X11able3
 	method(#dual) class.
 }
 
+class QQQ(Object)
+{
+}
+
+extend QQQ [X11able]
+{
+
+method(#dual) abc { ^nil }
+method(#dual,#liberal) def(x, z) { ^nil }
+}
 
 class X11(Object) [X11able,selfns.X11able3] from 'x11'
 {
@@ -32,6 +42,7 @@ class X11(Object) [X11able,selfns.X11able3] from 'x11'
 	var event_loop_sem, event_loop_proc.
 	var llevent_blocks.
 
+
 method(#dual) abc { ^nil }
 method(#dual,#liberal) def(x, z) { ^nil }
 ###method(#dual) abc3 { ^nil }
diff --git a/moo/lib/comp.c b/moo/lib/comp.c
index 0e67caa..8e0465a 100644
--- a/moo/lib/comp.c
+++ b/moo/lib/comp.c
@@ -8021,6 +8021,11 @@ static int __compile_class_definition (moo_t* moo, int class_type)
 
 		cc->super_oop = cc->self_oop->superclass;
 		MOO_ASSERT (moo, cc->super_oop == moo->_nil || MOO_CLASSOF(moo, cc->super_oop) == moo->_class);
+		
+		if (TOKEN_TYPE(moo) == MOO_IOTOK_LBRACK)
+		{
+			if (process_class_interfaces(moo) <= -1) return -1;
+		}
 	}
 	else
 	{