diff --git a/libasn1parser/asn1p_expr.h b/libasn1parser/asn1p_expr.h
index 213f6a7..3be9672 100644
--- a/libasn1parser/asn1p_expr.h
+++ b/libasn1parser/asn1p_expr.h
@@ -59,6 +59,7 @@
 	ASN_CONSTR_SET,			/* SET */
 	ASN_CONSTR_SEQUENCE_OF,		/* SEQUENCE OF */
 	ASN_CONSTR_SET_OF,		/* SET OF */
+	ASN_CONSTR_OPEN_TYPE,
 
 	/*
 	 * ASN.1 Basic types