diff --git a/libasn1parser/asn1p_module.h b/libasn1parser/asn1p_module.h
index e34ffde..618c6e7 100644
--- a/libasn1parser/asn1p_module.h
+++ b/libasn1parser/asn1p_module.h
@@ -71,6 +71,12 @@
 	TQ_ENTRY(struct asn1p_module_s)
 		mod_next;
 
+	/*
+	 * Internally useful properties.
+	 */
+	enum {
+	  MT_STANDARD_MODULE = 0x01,	/* Module came from standard-modules */
+	} _tags;
 } asn1p_module_t;
 
 /*