--- fat.c.atari	2009-08-29 17:19:17.000000000 +0200
+++ fat.c	2010-01-15 18:09:12.000000000 +0100
@@ -653,6 +653,9 @@
 		 * and 0xff.  Do not consider this as an error */
 		return 0;
 	
+	/* Some Atari ST disks are actually using f7/f9; ignore this
+	   "sanity check" to read them...
+
 	if((address[0] != boot->boot.descr && boot->boot.descr >= 0xf0 &&
 	    ((address[0] != 0xf9 && address[0] != 0xf7) 
 	     || boot->boot.descr != 0xf0)) || address[0] < 0xf0) {
@@ -661,7 +664,7 @@
 				address[0],
 				boot->boot.descr);
 		return -1;
-	}
+	} */
 
 	if(address[1] != 0xff || address[2] != 0xff){
 		fprintf(stderr,"Initial byte of fat is not 0xff\n");