diff --git a/include/osmocom/gsm/gsup.h b/include/osmocom/gsm/gsup.h
index 51871e447..37e474c2a 100644
--- a/include/osmocom/gsm/gsup.h
+++ b/include/osmocom/gsm/gsup.h
@@ -98,6 +98,8 @@ enum osmo_gsup_iei {
 	OSMO_GSUP_SM_RP_CAUSE_IE		= 0x44,
 	OSMO_GSUP_SM_RP_MMS_IE			= 0x45,
 	OSMO_GSUP_SM_ALERT_RSN_IE		= 0x46,
+
+	_OSMO_GSUP_IEI_END_MARKER
 };
 
 /*! GSUP message type */
diff --git a/tests/gsup/gsup_test.c b/tests/gsup/gsup_test.c
index b3a8c772e..079a70317 100644
--- a/tests/gsup/gsup_test.c
+++ b/tests/gsup/gsup_test.c
@@ -401,11 +401,7 @@ static void test_gsup_messages_dec_enc(void)
 					osmo_hexdump(t->data + j, ie_end - j));
 
 				OSMO_ASSERT(j <= ie_end - 2);
-				/**
-				 * FIXME: share the maximal IE value somehow
-				 * in order to avoid manual updating of this
-				 */
-				OSMO_ASSERT(t->data[j+0] <= OSMO_GSUP_SM_ALERT_RSN_IE);
+				OSMO_ASSERT(t->data[j+0] < _OSMO_GSUP_IEI_END_MARKER);
 				OSMO_ASSERT(t->data[j+1] <= ie_end - j - 2);
 
 				ie_end = j;