diff --git a/lib/libdisk/open_disk.c b/lib/libdisk/open_disk.c
index 6ffe88d..10ce2f4 100644
--- a/lib/libdisk/open_disk.c
+++ b/lib/libdisk/open_disk.c
@@ -128,6 +128,14 @@ Int_Open_Disk(const char *name, char *conftxt)
 	}
 
 	/*
+	 * In case BIOS have no data on the heads and sector count, set a
+	 * reasonable default.
+	 */
+	if (d->bios_hd == 0)
+		d->bios_hd = 16;
+	if (d->bios_sect == 0)
+		d->bios_sect = 63;
+	/*
 	 * Calculate the number of cylinders this disk must have. If we have
 	 * an obvious insanity, we set the number of cylinders to zero.
 	 */