diff --git a/VAX/vax_defs.h b/VAX/vax_defs.h
index 36b636d4..2ae104af 100644
--- a/VAX/vax_defs.h
+++ b/VAX/vax_defs.h
@@ -1036,7 +1036,7 @@ extern t_stat cpu_show_instruction_set (FILE *st, UNIT *uptr, int32 val, CONST v
 extern t_stat cpu_set_instruction_set (UNIT *uptr, int32 val, CONST char *cptr, void *desc);
 extern t_stat cpu_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, const char *cptr);
 extern t_stat cpu_model_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, const char *cptr);
-extern void vax_init();
+extern void vax_init(void);
 extern const uint32 byte_mask[33];
 extern int32 autcon_enb;                                /* autoconfig enable */
 extern int32 int_req[IPL_HLVL];                         /* intr, IPL 14-17 */