Index: src/libcfa/bits/containers.h
===================================================================
--- src/libcfa/bits/containers.h	(revision 13073be42dba9d23e1eb3322d700f265381ae024)
+++ src/libcfa/bits/containers.h	(revision 8ebbfc4c887a4b7e35a28345e0a8a272f1abb11f)
@@ -183,4 +183,9 @@
 		verify( *tail == NULL );
 		return val;
+	}
+
+	forall(dtype T | is_node(T))
+	static inline bool ?!=?( __queue(T) & this, zero_t zero ) with( this ) {
+		return head != 0;
 	}
 #endif