do not use reserved identifiers
diff --git a/libasn1fix/asn1fix_bitstring.h b/libasn1fix/asn1fix_bitstring.h
index 1230856..79b3d00 100644
--- a/libasn1fix/asn1fix_bitstring.h
+++ b/libasn1fix/asn1fix_bitstring.h
@@ -1,6 +1,6 @@
-#ifndef	_ASN1FIX_BIT_STRING_H_
-#define	_ASN1FIX_BIT_STRING_H_
+#ifndef	ASN1FIX_BIT_STRING_H
+#define	ASN1FIX_BIT_STRING_H
 
 int asn1f_fix_bit_string(arg_t *);
 
-#endif	/* _ASN1FIX_BIT_STRING_H_ */
+#endif	/* ASN1FIX_BIT_STRING_H */