diff --git a/include/osmocom/sgsn/sgsn.h b/include/osmocom/sgsn/sgsn.h
index 7e0b5d4..829a8fc 100644
--- a/include/osmocom/sgsn/sgsn.h
+++ b/include/osmocom/sgsn/sgsn.h
@@ -9,6 +9,12 @@
 #include <osmocom/sgsn/oap_client.h>
 #include <osmocom/sgsn/common.h>
 
+#include "../../bscconfig.h"
+
+#if BUILD_IU
+#include <osmocom/ranap/iu_client.h>
+#endif
+
 #include <ares.h>
 #include <gtp.h>
 
@@ -113,9 +119,11 @@
 		int p2;
 	} dcomp_v42bis;
 
+#if BUILD_IU
 	struct {
-		int rab_assign_addr_enc;
+		enum ranap_nsap_addr_enc rab_assign_addr_enc;
 	} iu;
+#endif
 };
 
 struct sgsn_instance {