diff --git a/channels/chan_pjsip.c b/channels/chan_pjsip.c
index 96500b4edf..42e329e50a 100644
--- a/channels/chan_pjsip.c
+++ b/channels/chan_pjsip.c
@@ -2122,6 +2122,7 @@ static int unload_module(void)
 
 	ast_sip_session_unregister_supplement(&chan_pjsip_supplement);
 	ast_sip_session_unregister_supplement(&pbx_start_supplement);
+	ast_sip_session_unregister_supplement(&chan_pjsip_ack_supplement);
 
 	ast_custom_function_unregister(&chan_pjsip_dial_contacts_function);
 	ast_channel_unregister(&chan_pjsip_tech);