diff --git a/elks/arch/i86/drivers/block/bios.c b/elks/arch/i86/drivers/block/bios.c
index 65a3be4e3..97ff09954 100644
--- a/elks/arch/i86/drivers/block/bios.c
+++ b/elks/arch/i86/drivers/block/bios.c
@@ -223,21 +223,20 @@ int INITPROC bios_gethdinfo(struct drive_infot *drivep) {
     return ndrives;
 }
 
-static void BFPROC bios_disk_park(struct drive_infot *drive)
+void BFPROC bios_disk_park_all(void)
 {
-    /* int 13 AH=0xC supports only 10 bits for cyl */
-    if (drive->cylinders > 1024 || drive->fdtype != -1) return;
-    BD_AX = 0x0C << 8;
-    BD_CX = ((drive->cylinders & 0xFF) << 8) | ((drive->cylinders & 0x300) >> 2) | 0x1; /* 0x1 = sector */
-    BD_DX = bios_drive_map[drive - drive_info];
-    call_bios(&bdt);
-}
-
-void bios_disk_park_all(void)
-{
-    int i;
-    for (i = 0; i < NUM_DRIVES; ++i)
-        bios_disk_park(&drive_info[i]);
+    struct drive_infot *drivep;
+    unsigned int cyl;
+
+    for (drivep = drive_info; drivep < &drive_info[NUM_DRIVES]; drivep++) {
+        if (drivep->fdtype != -1)       /* hard drives only */
+            continue;
+        cyl = drivep->cylinders - 1;    /* expects zero-based cylinder */
+        BD_AX = 0x0C << 8;
+        BD_CX = ((cyl & 0xFF) << 8) | ((cyl & 0x300) >> 2) | 1; /* 1 = sector */
+        BD_DX = bios_drive_map[drivep - drive_info];
+        call_bios(&bdt);
+    }
 }
 
 #endif
diff --git a/elks/include/linuxmt/biosparm.h b/elks/include/linuxmt/biosparm.h
index 7b8255f31..ed41ff693 100644
--- a/elks/include/linuxmt/biosparm.h
+++ b/elks/include/linuxmt/biosparm.h
@@ -87,6 +87,6 @@ void BFPROC bios_copy_ddpt(void);
 struct drive_infot;
 void BFPROC bios_switch_device98(int target, unsigned int device,
         struct drive_infot *drivep);
-void bios_disk_park_all(void);
+void BFPROC bios_disk_park_all(void);
 
 #endif