diff --git a/externals/k_jack~/k_jack~.c b/externals/k_jack~/k_jack~.c
index 0fd9d2208b04ac92666d1163cb086b3c696a8f8d..8f6d140754bc162631785bdc59cf1ef5a1313c78 100644
--- a/externals/k_jack~/k_jack~.c
+++ b/externals/k_jack~/k_jack~.c
@@ -414,7 +414,7 @@ void k_jack_tilde_setup(void){
   k_jack_class = class_new(gensym("k_jack~"), (t_newmethod)k_jack_new, (t_method)k_jack_free,
 			  sizeof(t_k_jack), 0, A_SYMBOL, 0);
   CLASS_MAINSIGNALIN(k_jack_class, t_k_jack, x_float);
-  class_addmethod(k_jack_class, (t_method)k_jack_dsp, gensym("dsp"), 0);
+  class_addmethod(k_jack_class, (t_method)k_jack_dsp, gensym("dsp"), A_CANT, 0);
   
   class_sethelpsymbol(k_jack_class, gensym("help-k_jack~.pd"));