--- a/os9/makerom.c	Wed Jul 11 21:16:06 2018 +0900
+++ b/os9/makerom.c	Thu Jul 12 06:25:25 2018 +0900
@@ -287,12 +287,17 @@
 #endif 
         pos += cur->size;
      }
-     while(pos++ & 0x1fff) fputc(0xff,romfile);
+     while(pos++ & 0xff) fputc(0xff,romfile);
  }
  if (level==1) 
      printf("boot rom from 0x%lx\n",0x10000-ftell(romfile)); 
- else
-     printf("boot rom from 0xc000 size 0x%lx\n",ftell(romfile)); 
+ else {
+     long size;
+     printf("boot rom from 0xc000 size 0x%lx\n",(size=ftell(romfile))); 
+     if (size > 0x4d00 + 0x2000) {
+         printf(" was too big. make it less than 0x6d00\n");
+     } 
+ }
  fclose(romfile);
  return 0;
 }