diff --git a/firmware/test/fat/ata-sim.c b/firmware/test/fat/ata-sim.c
index 10bc3d9dc5..04cdadb6ce 100644
--- a/firmware/test/fat/ata-sim.c
+++ b/firmware/test/fat/ata-sim.c
@@ -10,7 +10,11 @@ static FILE* file;
 
 int ata_read_sectors(unsigned long start, unsigned char count, void* buf)
 {
-    DEBUGF("[Reading block 0x%lx, %d]\n", start, count); 
+    if ( count > 1 )
+        DEBUGF("[Reading %d blocks: 0x%lx to 0x%lx]\n",
+               count, start, start+count-1); 
+    else
+        DEBUGF("[Reading block 0x%lx, %d]\n", start, count); 
 
     if(fseek(file,start*BLOCK_SIZE,SEEK_SET)) {
         perror("fseek");
@@ -26,7 +30,11 @@ int ata_read_sectors(unsigned long start, unsigned char count, void* buf)
 
 int ata_write_sectors(unsigned long start, unsigned char count, void* buf)
 {
-    DEBUGF("[Writing block 0x%lx, %d]\n", start, count); 
+    if ( count > 1 )
+        DEBUGF("[Writing %d blocks: 0x%lx to 0x%lx]\n",
+               count, start, start+count-1); 
+    else
+        DEBUGF("[Writing block 0x%lx]\n", start); 
 
     if (start == 0)
         panicf("Writing on sector 0!\n");
diff --git a/firmware/test/fat/main.c b/firmware/test/fat/main.c
index ab71308abb..68cef1f08c 100644
--- a/firmware/test/fat/main.c
+++ b/firmware/test/fat/main.c
@@ -125,9 +125,9 @@ int dbg_mkfile(char* name, int num)
     return 0;
 }
 
-int dbg_chkfile(char* name)
+int dbg_chkfile(char* name, int size)
 {
-    char text[8192];
+    char text[81920];
     int i;
     int x=0;
     int block=0;
@@ -136,6 +136,13 @@ int dbg_chkfile(char* name)
         DEBUGF("Failed opening file\n");
         return -1;
     }
+
+    if (size) {
+        lseek(fd, size*512, SEEK_SET);
+        x = size * 1024 / 16;
+        LDEBUGF("Check base is %x\n",x);
+    }
+
     while (1) {
         int rc = read(fd, text, sizeof text);
         DEBUGF("read %d bytes\n",rc);
@@ -343,8 +350,12 @@ int dbg_cmd(int argc, char *argv[])
 
     if (!strcasecmp(cmd, "chkfile"))
     {
-        if (arg1)
-            return dbg_chkfile(arg1);
+        if (arg1) {
+            if (arg2)
+                return dbg_chkfile(arg1, atoi(arg2));
+            else
+                return dbg_chkfile(arg1, 0);
+        }
     }
 
     return 0;
diff --git a/firmware/test/fat/test.sh b/firmware/test/fat/test.sh
index 2f58b3cb81..f723f69ec3 100644
--- a/firmware/test/fat/test.sh
+++ b/firmware/test/fat/test.sh
@@ -34,22 +34,27 @@ runtests() {
     echo ---Test: create a 10K file
     try mkfile /apa.txt 10
     check
-    try chkfile /apa.txt
+    try chkfile /apa.txt 10
 
     echo ---Test: create a 1K file
     try mkfile /bpa.txt 1
     check
-    try chkfile /bpa.txt
+    try chkfile /bpa.txt 1
 
     echo ---Test: create a 40K file
     try mkfile /cpa.txt 40
     check
-    try chkfile /cpa.txt
+    try chkfile /cpa.txt 40
+
+    echo ---Test: create a 400K file
+    try mkfile /dpa.txt 400
+    check
+    try chkfile /dpa.txt 400
 
     echo ---Test: truncate previous 40K file to 20K
     try mkfile /cpa.txt 20
     check
-    try chkfile /cpa.txt
+    try chkfile /cpa.txt 20
 
     echo ---Test: truncate previous 20K file to 0K
     try mkfile /cpa.txt 0
@@ -59,14 +64,15 @@ runtests() {
     try chkfile /bpa.txt
 
     LOOP=50
+    SIZE=50
 
-    echo ---Test: create $LOOP 40k files
+    echo ---Test: create $LOOP $SIZE k files
     for i in `seq 1 $LOOP`;
     do
         echo ---Test: $i/$LOOP ---
-        try mkfile /rockbox.$i 40
+        try mkfile /rockbox.$i $SIZE
         check
-        try chkfile /rockbox.$i
+        try chkfile /rockbox.$i $SIZE
     done
 
 }