diff --git a/skeletons/T61String.h b/skeletons/T61String.h
index 3c2d72f..27f7cc6 100644
--- a/skeletons/T61String.h
+++ b/skeletons/T61String.h
@@ -14,6 +14,7 @@
 typedef OCTET_STRING_t T61String_t;	/* Implemented via OCTET STRING */
 
 extern asn_TYPE_descriptor_t asn_DEF_T61String;
+extern asn_TYPE_operation_t asn_OP_T61String;
 
 #define T61String_free          OCTET_STRING_free
 #define T61String_print         OCTET_STRING_print