diff --git a/res/res_pjsip_registrar.c b/res/res_pjsip_registrar.c
index 078e13ee28..76d8b04a6b 100644
--- a/res/res_pjsip_registrar.c
+++ b/res/res_pjsip_registrar.c
@@ -25,6 +25,7 @@
 
 #include "asterisk.h"
 
+#include <signal.h>
 #include <pjsip.h>
 #include <pjsip_ua.h>