diff --git a/libasn1parser/asn1p_constr.h b/libasn1parser/asn1p_constr.h
index d375678..c83d58b 100644
--- a/libasn1parser/asn1p_constr.h
+++ b/libasn1parser/asn1p_constr.h
@@ -57,6 +57,7 @@
 	int el_size;	/* Size of the allocated (elements) */
 
 	int _lineno;	/* Position in a source file */
+	int _compile_mark;	/* Marker used by the compiler */
 } asn1p_constraint_t;
 
 /* Human-readable constraint type description */