diff --git a/src/NULL.h b/src/NULL.h
new file mode 100644
index 0000000..131e775
--- /dev/null
+++ b/src/NULL.h
@@ -0,0 +1,33 @@
+/*-
+ * Copyright (c) 2003 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	ASN_TYPE_NULL_H
+#define	ASN_TYPE_NULL_H
+
+#include <asn_application.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * The value of the NULL type is meaningless: see BOOLEAN if you want to
+ * carry true/false semantics.
+ */
+typedef int NULL_t;
+
+extern asn_TYPE_descriptor_t asn_DEF_NULL;
+
+asn_struct_print_f NULL_print;
+der_type_encoder_f NULL_encode_der;
+xer_type_decoder_f NULL_decode_xer;
+xer_type_encoder_f NULL_encode_xer;
+per_type_decoder_f NULL_decode_uper;
+per_type_encoder_f NULL_encode_uper;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* NULL_H */