diff --git a/writeboost-cli/data/sample.cache.uninit b/writeboost-cli/data/sample.cache.uninit
index e69de29..3301331 100644
Binary files a/writeboost-cli/data/sample.cache.uninit and b/writeboost-cli/data/sample.cache.uninit differ
diff --git a/writeboost-cli/src/sub/check/mod.rs b/writeboost-cli/src/sub/check/mod.rs
index 13c68ce..ff4dd3a 100644
--- a/writeboost-cli/src/sub/check/mod.rs
+++ b/writeboost-cli/src/sub/check/mod.rs
@@ -19,13 +19,13 @@ enum CheckError {
         "segment {seg_id} is broken. checksum: computed={computed_checksum}, expected={expected_checksum}"
     )]
     CacheBlockBroken {
-        seg_id: i32,
+        seg_id: u64,
         computed_checksum: u32,
         expected_checksum: u32,
     },
 }
 
-fn do_check(devname: &str, seg_id: i32) -> Result<(), CheckError> {
+fn do_check(devname: &str, seg_id: u64) -> Result<(), CheckError> {
     let cache_dev = CacheDevice::new(devname.to_owned());
 
     let mut f = File::open(&devname).expect(&format!("Device {} not found", &devname));
@@ -74,7 +74,7 @@ mod tests {
     #[test]
     fn test_check() {
         let devname = "data/sample.cache.226";
-        let seg_id = 1;
+        let seg_id = 73;
         let res = do_check(&devname, seg_id);
         assert!(res.is_ok());
     }
@@ -82,7 +82,7 @@ mod tests {
     #[test]
     fn test_uninitialized() {
         let devname = "data/sample.cache.uninit";
-        let seg_id = 0;
+        let seg_id = 3;
         let res = do_check(&devname, seg_id);
         assert!(matches!(res, Err(CheckError::NotInitialized)));
     }
@@ -94,7 +94,7 @@ pub struct CommandArgs {
     #[arg(help = "Path to the cache device")]
     cachedev: String,
     #[arg(help = "Segment id")]
-    segid: i32,
+    segid: u64,
 }
 
 pub fn run(args: CommandArgs) {
@@ -103,10 +103,10 @@ pub fn run(args: CommandArgs) {
 
     match do_check(&devname, id) {
         Ok(()) => {}
-        Err(CheckError::NotInitialized) => {
+        Err(e @ CheckError::NotInitialized) => {
             // Since segments are zero-ed out at formatting,
             // if the segment is all zeros, it is considered still unused.
-            eprintln!("segment is not initialized");
+            eprintln!("{e}");
         }
         Err(e) => {
             panic!("{e}")
diff --git a/writeboost-cli/src/sub/dump/mod.rs b/writeboost-cli/src/sub/dump/mod.rs
index 6ef03d0..60baa98 100644
--- a/writeboost-cli/src/sub/dump/mod.rs
+++ b/writeboost-cli/src/sub/dump/mod.rs
@@ -7,14 +7,14 @@ pub struct CommandArgs {
     #[arg(help = "Path to the cache device")]
     cachedev: String,
     #[arg(help = "Metablock index")]
-    mbidx: i32,
+    mbidx: u32,
     #[arg(long, help = "MBIDX is relative to this SEGID (default is 1)")]
     #[arg(default_value_t = 1)]
-    segid: i32,
+    segid: u64,
 }
 
 pub fn run(args: CommandArgs) {
-    let mb_idx: i32 = args.mbidx;
+    let mb_idx: u32 = args.mbidx;
     let cache_dev = {
         let devname = args.cachedev;
         CacheDevice::new(devname.to_owned())
@@ -22,7 +22,7 @@ pub fn run(args: CommandArgs) {
 
     let mut base_id = args.segid;
 
-    base_id += mb_idx / 127;
+    base_id += mb_idx as u64 / 127;
     let idx_inseg = mb_idx % 127;
     let start_byte = (cache_dev.calc_segment_start(base_id) << 9) + ((1 + idx_inseg) << 12);
 
diff --git a/writeboost-cli/src/sub/meta/mod.rs b/writeboost-cli/src/sub/meta/mod.rs
index daa319a..f29f0cf 100644
--- a/writeboost-cli/src/sub/meta/mod.rs
+++ b/writeboost-cli/src/sub/meta/mod.rs
@@ -12,12 +12,12 @@ pub struct CommandArgs {
     #[arg(help = "Path to the cache device")]
     cachedev: String,
     #[arg(help = "Segment id. 0 means the superblock")]
-    segid: i32,
+    segid: u64,
 }
 
 pub fn run(args: CommandArgs) {
     let devname: String = args.cachedev;
-    let id: i32 = args.segid;
+    let id = args.segid;
 
     let cache_dev = CacheDevice::new(devname.to_owned());
 
@@ -56,9 +56,9 @@ pub fn run(args: CommandArgs) {
         let (header, metablocks) = Segment::from_buf(&buf);
 
         println!("[segment header]");
-        println!("id        = {}", header.id);
-        println!("checksumx = {}", header.checksum);
-        println!("length    = {}", header.length);
+        println!("id       = {}", header.id);
+        println!("checksum = {}", header.checksum);
+        println!("length   = {}", header.length);
 
         for (i, metablock) in metablocks.iter().enumerate() {
             println!(
diff --git a/writeboost-cli/src/utils.rs b/writeboost-cli/src/utils.rs
index 4f82146..e883d7f 100644
--- a/writeboost-cli/src/utils.rs
+++ b/writeboost-cli/src/utils.rs
@@ -22,7 +22,7 @@ impl BlockDevice {
         self.name.to_owned()
     }
 
-    pub fn size(&self) -> i64 {
+    pub fn size(&self) -> u64 {
         use std::str::FromStr;
         let output: Vec<u8> = Command::new("blockdev")
             .arg("--getsz")
@@ -34,7 +34,7 @@ impl BlockDevice {
             .expect("Invalid utf8 output")
             .to_string();
         let output = output.trim_end();
-        i64::from_str(output).expect("Couldn't parse as i64")
+        u64::from_str(output).expect("Couldn't parse as u64")
     }
 }
 
@@ -49,13 +49,13 @@ impl CacheDevice {
         }
     }
 
-    fn nr_segments(&self) -> i32 {
-        ((self.dev.size() - (1 << 11)) / (1 << 10)) as i32
+    fn nr_segments(&self) -> u32 {
+        ((self.dev.size() - (1 << 11)) / (1 << 10)) as u32
     }
 
-    pub fn calc_segment_start(&self, id: i32) -> i32 {
-        let idx = (id - 1) % self.nr_segments();
-        (1 << 11) + (idx * (1 << 10))
+    pub fn calc_segment_start(&self, id: u64) -> u32 {
+        let idx = (id - 1) % self.nr_segments() as u64;
+        (1 << 11) + (idx as u32 * (1 << 10))
     }
 }