diff --git a/src/libmsc/gsm_04_11_gsup.c b/src/libmsc/gsm_04_11_gsup.c
index 7a47e93..0f18912 100644
--- a/src/libmsc/gsm_04_11_gsup.c
+++ b/src/libmsc/gsm_04_11_gsup.c
@@ -33,6 +33,7 @@
 #include <osmocom/msc/vlr.h>
 #include <osmocom/msc/msub.h>
 #include <osmocom/msc/gsup_client_mux.h>
+#include <osmocom/msc/msc_a.h>
 
 /* Common helper for preparing to be encoded GSUP message */
 static void gsup_sm_msg_init(struct osmo_gsup_message *gsup_msg,