diff --git a/sys/boot/i386/libi386/biosdisk.c b/sys/boot/i386/libi386/biosdisk.c
index 6d381d45cc70..25faefc32913 100644
--- a/sys/boot/i386/libi386/biosdisk.c
+++ b/sys/boot/i386/libi386/biosdisk.c
@@ -867,7 +867,7 @@ bd_read(struct open_disk *od, daddr_t dblk, int blks, caddr_t dest)
 	 */
 	x = min(FLOPPY_BOUNCEBUF, (unsigned)blks);
 	bbuf = malloc(x * 2 * BIOSDISK_SECSIZE);
-	if (((u_int32_t)VTOP(bbuf) & 0xffff0000) == ((u_int32_t)VTOP(dest + x * BIOSDISK_SECSIZE) & 0xffff0000)) {
+	if (((u_int32_t)VTOP(bbuf) & 0xffff0000) == ((u_int32_t)VTOP(bbuf + x * BIOSDISK_SECSIZE) & 0xffff0000)) {
 	    breg = bbuf;
 	} else {
 	    breg = bbuf + x * BIOSDISK_SECSIZE;
@@ -1000,7 +1000,7 @@ bd_write(struct open_disk *od, daddr_t dblk, int blks, caddr_t dest)
 
 	x = min(FLOPPY_BOUNCEBUF, (unsigned)blks);
 	bbuf = malloc(x * 2 * BIOSDISK_SECSIZE);
-	if (((u_int32_t)VTOP(bbuf) & 0xffff0000) == ((u_int32_t)VTOP(dest + x * BIOSDISK_SECSIZE) & 0xffff0000)) {
+	if (((u_int32_t)VTOP(bbuf) & 0xffff0000) == ((u_int32_t)VTOP(bbuf + x * BIOSDISK_SECSIZE) & 0xffff0000)) {
 	    breg = bbuf;
 	} else {
 	    breg = bbuf + x * BIOSDISK_SECSIZE;