diff --git a/lib/asn1/gen_locl.h b/lib/asn1/gen_locl.h
index 0fd9b2cd2..288631e98 100644
--- a/lib/asn1/gen_locl.h
+++ b/lib/asn1/gen_locl.h
@@ -92,7 +92,7 @@ void gen_template_import(const Symbol *);
 
 
 extern FILE *privheaderfile, *headerfile, *codefile, *logfile, *templatefile;
-const char *fuzzer_string;
+extern const char *fuzzer_string;
 extern int support_ber;
 extern int template_flag;
 extern int rfc1510_bitstring;