diff --git a/libasn1compiler/asn1c_ioc.h b/libasn1compiler/asn1c_ioc.h
index face3a1..d1a4b4c 100644
--- a/libasn1compiler/asn1c_ioc.h
+++ b/libasn1compiler/asn1c_ioc.h
@@ -15,5 +15,8 @@
 int emit_ioc_table(arg_t *arg, asn1p_expr_t *context,
                     asn1c_ioc_table_and_objset_t);
 
+const asn1p_ref_t *asn1c_get_information_object_set_reference_from_constraint(
+    arg_t *arg, const asn1p_constraint_t *ct);
+
 
 #endif	/* ASN1_IOC_H */