diff --git a/firmware/test/fat/ata-sim.c b/firmware/test/fat/ata-sim.c
index 63abc58084..aac7fba0f4 100644
--- a/firmware/test/fat/ata-sim.c
+++ b/firmware/test/fat/ata-sim.c
@@ -8,7 +8,7 @@
 
 static FILE* file;
 
-int ata_read_sectors(unsigned long start, unsigned char count, void* buf)
+int ata_read_sectors(unsigned long start, int count, void* buf)
 {
     if ( count > 1 )
         DEBUGF("[Reading %d blocks: 0x%lx to 0x%lx]\n",
@@ -28,7 +28,7 @@ int ata_read_sectors(unsigned long start, unsigned char count, void* buf)
     return 0;
 }
 
-int ata_write_sectors(unsigned long start, unsigned char count, void* buf)
+int ata_write_sectors(unsigned long start, int count, void* buf)
 {
     if ( count > 1 )
         DEBUGF("[Writing %d blocks: 0x%lx to 0x%lx]\n",
diff --git a/firmware/test/fat/main.c b/firmware/test/fat/main.c
index 520454541f..9c1b983925 100644
--- a/firmware/test/fat/main.c
+++ b/firmware/test/fat/main.c
@@ -331,40 +331,47 @@ int dbg_append(char* name)
 int dbg_test(char* name)
 {
     int x=0;
-    int size, fd, rc;
-    char buf[4096];
+    int j;
+    int fd;
+    char text[BUFSIZE+1];
 
-    fd = open(name,O_RDWR);
-    if (fd<0) {
-        DEBUGF("Failed opening file\n");
-        return -1;
-    }
+    for (j=0; j<5; j++) {
+        int num = 40960;
 
-    size = lseek(fd, -1024, SEEK_END);
-    size &= ~7;
-    DEBUGF("File is %d bytes\n", size);
-    x = size / CHUNKSIZE;
-    LDEBUGF("Check base is %x (%d)\n",x,size);
+        fd = open(name,O_WRONLY|O_CREAT|O_APPEND);
+        if (fd<0) {
+            DEBUGF("Failed opening file\n");
+            return -1;
+        }
 
-    rc = read(fd, buf, sizeof buf);
-    if ( rc < 0 )
-        panicf("Failed reading data\n");
-    if ( rc == 0 )
-        DEBUGF("EOF\n");
+        while ( num ) {
+            int rc, i;
+            int len = num > BUFSIZE ? BUFSIZE : num;
 
-    rc = read(fd, buf, sizeof buf);
-    if ( rc < 0 )
-        panicf("Failed reading data\n");
-    if ( rc == 0 )
-        DEBUGF("EOF\n");
+            for (i=0; i<len/CHUNKSIZE; i++ )
+                sprintf(text+i*CHUNKSIZE,"%c%06x,",name[1],x++);
 
-    rc = write(fd, buf, sizeof buf);
-    if ( rc < 0 )
-        panicf("Failed writing data\n");
-    if ( rc == 0 )
-        DEBUGF("Nothing written!\n");
+            rc = write(fd, text, len);
+            if ( rc < 0 ) {
+                DEBUGF("Failed writing data\n");
+                return -1;
+            }
+            else
+                if ( rc == 0 ) {
+                    DEBUGF("No space left\n");
+                    return -2;
+                }
+                else
+                    DEBUGF("wrote %d bytes\n",rc);
 
-    return close(fd);
+            num -= len;
+        }
+
+        if (close(fd) < 0)
+            return -1;
+    }    
+
+    return 0;
 }
 
 int dbg_dump(char* name, int offset)
@@ -511,6 +518,7 @@ int dbg_cmd(int argc, char *argv[])
                " wrtest <file>\n"
                " append <file>\n"
                " test <file>\n"
+               " ren <file> <newname>\n"
             );
         return -1;
     }
@@ -615,6 +623,12 @@ int dbg_cmd(int argc, char *argv[])
             return dbg_trunc(arg1, atoi(arg2));
     }
 
+    if (!strcasecmp(cmd, "ren"))
+    {
+        if (arg1 && arg2)
+            return rename(arg1, arg2);
+    }
+
     return 0;
 }
 
diff --git a/firmware/test/fat/test.sh b/firmware/test/fat/test.sh
index 7d9435b85d..6a26e7ff59 100644
--- a/firmware/test/fat/test.sh
+++ b/firmware/test/fat/test.sh
@@ -15,8 +15,9 @@ check() {
 }
 
 try() {
-    echo COMMAND: fat $1 $2 $3 >> $RESULT
-    ./fat $1 $2 $3 2>> $RESULT
+    echo COMMAND: fat $1 "$2" "$3"
+    echo COMMAND: fat $1 "$2" "$3" >> $RESULT
+    ./fat $1 "$2" "$3" 2>> $RESULT
     RETVAL=$?
     [ $RETVAL -ne 0 ] && fail
 }
@@ -26,6 +27,10 @@ buildimage() {
     mount -o loop $IMAGE $MOUNT
     echo "Filling it with /etc files"
     find /etc -type f -maxdepth 1 -exec cp {} $MOUNT \;
+    for i in `seq 1 120`;
+    do
+        echo apa > "$MOUNT/very $i long test filename so we can make sure they.work"
+    done
     mkdir $MOUNT/dir
     umount $MOUNT
 }
@@ -34,53 +39,63 @@ runtests() {
     rm $RESULT
 
     echo ---Test: create a 10K file
-    try mkfile /apa.txt 10
-    try mkfile /dir/apa.txt 10
+    try mkfile "/really long filenames rock" 10
     check
-    try chkfile /apa.txt 10
-    try chkfile /dir/apa.txt 8
+    try mkfile /dir/apa.monkey.me.now 10
+    check
+    try chkfile "/really long filenames rock" 10
+    try chkfile /dir/apa.monkey.me.now 8
 
     echo ---Test: create a 1K file
-    try mkfile /bpa.txt 1
+    try mkfile /bpa.rock 1
     check
-    try chkfile /bpa.txt 1
+    try chkfile /bpa.rock 1
 
     echo ---Test: create a 40K file
-    try mkfile /cpa.txt 40
+    try mkfile /cpa.rock 40
     check
-    try chkfile /cpa.txt 40
+    try chkfile /cpa.rock 40
 
     echo ---Test: create a 400K file
-    try mkfile /dpa.txt 400
+    try mkfile /dpa.rock 400
     check
-    try chkfile /dpa.txt 400
+    try chkfile /dpa.rock 400
 
-    echo ---Test: truncate previous 40K file to 20K
-    try mkfile /cpa.txt 20
+    echo ---Test: create a 1200K file
+    try mkfile /epa.rock 1200
     check
-    try chkfile /cpa.txt 20
+    try chkfile /epa.rock 1200
 
-    echo ---Test: truncate previous 20K file to 0K
-    try mkfile /cpa.txt 0
+    echo ---Test: rewrite first 20K of a 40K file
+    try mkfile /cpa.rock 20
     check
-    try chkfile /cpa.txt
-    try chkfile /apa.txt
-    try chkfile /bpa.txt
+    try chkfile /cpa.rock 20
+
+    echo ---Test: rewrite first sector of 40K file
+    try mkfile /cpa.rock 0
+    check
+    try chkfile /cpa.rock
+    try chkfile /apa.rock
+    try chkfile /bpa.rock
 
     LOOP=50
-    SIZE=70
+    SIZE=700
+
+    try del "/really long filenames rock"
 
     echo ---Test: create $LOOP $SIZE k files
     for i in `seq 1 $LOOP`;
     do
         echo ---Test: $i/$LOOP ---
-        try mkfile /rockbox.$i $SIZE
+        try mkfile "/rockbox rocks.$i" $SIZE
         check
-        try chkfile /rockbox.$i $SIZE
+        try chkfile "/rockbox rocks.$i" $SIZE
         check
-        try del /rockbox.$i
+        try del "/rockbox rocks.$i"
         check
-        try mkfile /rockbox.$i $SIZE
+        try mkfile "/rockbox rocks.$i" $SIZE
+        check
+        try ren "/rockbox rocks.$i" "$i is a new long filename!"
         check
     done
 
@@ -90,20 +105,20 @@ echo "Building test image (4 sector/cluster)"
 buildimage 4
 runtests
 
-echo "Building test image (128 sectors/cluster)"
-buildimage 128
-runtests
-
 echo "Building test image (32 sectors/cluster)"
 buildimage 32
 runtests
 
-echo "Building test image (8 sectors/cluster)"
-buildimage 8
-runtests
-
 echo "Building test image (1 sector/cluster)"
 buildimage 1
 runtests
 
+echo "Building test image (8 sectors/cluster)"
+buildimage 8
+runtests
+
+echo "Building test image (128 sectors/cluster)"
+buildimage 128
+runtests
+
 echo "== Test completed sucessfully =="