fixed multiple imports problem

diff --git a/libasn1parser/asn1p_y.h b/libasn1parser/asn1p_y.h
index 09ace78..49ab05a 100644
--- a/libasn1parser/asn1p_y.h
+++ b/libasn1parser/asn1p_y.h
@@ -23,8 +23,8 @@
    This special exception was added by the Free Software Foundation
    in version 1.24 of Bison.  */
 
-#ifndef BISON_Y_TAB_H
-# define BISON_Y_TAB_H
+#ifndef BISON_ASN_P_Y_H
+# define BISON_ASN_P_Y_H
 
 /* Tokens.  */
 #ifndef YYTOKENTYPE
@@ -274,5 +274,5 @@
 extern YYSTYPE asn1p_lval;
 
 
-#endif /* not BISON_Y_TAB_H */
+#endif /* not BISON_ASN_P_Y_H */