diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 80156c815f8e392bc01809cbcc31b87ed3757e9a..4a60a2503e7733461a8b75866b236cce77e19c81 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -567,15 +567,16 @@ get_vfatname(fsdata *mydata, int curclust, __u8 *cluster,
 }
 
 /* Calculate short name checksum */
-static __u8 mkcksum(const char *str)
+static __u8 mkcksum(const char name[8], const char ext[3])
 {
 	int i;
 
 	__u8 ret = 0;
 
-	for (i = 0; i < 11; i++) {
-		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + str[i];
-	}
+	for (i = 0; i < sizeof(name); i++)
+		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
+	for (i = 0; i < sizeof(ext); i++)
+		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
 
 	return ret;
 }
@@ -678,7 +679,8 @@ static dir_entry *get_dentfromdir(fsdata *mydata, int startsect,
 				return NULL;
 			}
 #ifdef CONFIG_SUPPORT_VFAT
-			if (dols && mkcksum(dentptr->name) == prevcksum) {
+			__u8 csum = mkcksum(dentptr->name, dentptr->ext);
+			if (dols && csum == prevcksum) {
 				prevcksum = 0xffff;
 				dentptr++;
 				continue;
@@ -946,13 +948,16 @@ do_fat_read_at(const char *filename, unsigned long pos, void *buffer,
 
 		for (i = 0; i < DIRENTSPERBLOCK; i++) {
 			char s_name[14], l_name[VFAT_MAXLEN_BYTES];
+			__u8 csum;
 
 			l_name[0] = '\0';
 			if (dentptr->name[0] == DELETED_FLAG) {
 				dentptr++;
 				continue;
 			}
-			if ((dentptr->attr & ATTR_VOLUME)) {
+
+			csum = mkcksum(dentptr->name, dentptr->ext);
+			if (dentptr->attr & ATTR_VOLUME) {
 #ifdef CONFIG_SUPPORT_VFAT
 				if ((dentptr->attr & ATTR_VFAT) == ATTR_VFAT &&
 				    (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
@@ -1015,8 +1020,7 @@ do_fat_read_at(const char *filename, unsigned long pos, void *buffer,
 				goto exit;
 			}
 #ifdef CONFIG_SUPPORT_VFAT
-			else if (dols == LS_ROOT &&
-				 mkcksum(dentptr->name) == prevcksum) {
+			else if (dols == LS_ROOT && csum == prevcksum) {
 				prevcksum = 0xffff;
 				dentptr++;
 				continue;
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 5829adf1a16252e3b2d9f6db7909c1fe1a590b32..4a1bda0a37effd984885800ec4679be6f0f71666 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -335,7 +335,7 @@ fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 
 	/* Get short file name and checksum value */
 	strncpy(s_name, (*dentptr)->name, 16);
-	checksum = mkcksum(s_name);
+	checksum = mkcksum((*dentptr)->name, (*dentptr)->ext);
 
 	do {
 		memset(slotptr, 0x00, sizeof(dir_slot));