diff --git a/include/osmocom/gprs/gprs_ns_frgre.h b/include/osmocom/gprs/gprs_ns_frgre.h
index d48ce08..8cf54c7 100644
--- a/include/osmocom/gprs/gprs_ns_frgre.h
+++ b/include/osmocom/gprs/gprs_ns_frgre.h
@@ -2,4 +2,7 @@
 
 #pragma once
 
+struct gprs_nsvc;
+struct msgb;
+
 int gprs_ns_frgre_sendmsg(struct gprs_nsvc *nsvc, struct msgb *msg);