diff --git a/src/main.rs b/src/main.rs
index dec8992..4fd38cf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,6 +2,7 @@ use std::{
     cmp::{max, min},
     collections::{HashMap, HashSet},
     io::{stdout, Write},
+    os::unix::fs::FileTypeExt,
     path::{Path, PathBuf},
     str::FromStr,
     sync::Arc,
@@ -331,11 +332,27 @@ async fn main() -> anyhow::Result<()> {
                 });
             }
 
-            let file_size = target_file.file.metadata().unwrap().len();
+            let is_blockdevice = std::fs::metadata(target_file.file.as_path())
+                .unwrap()
+                .file_type()
+                .is_block_device();
+
+            let file_size = if is_blockdevice {
+                let sectors: u64 = std::fs::read_to_string(format!(
+                    "/sys/block/{}/size",
+                    target_file.file.file_name().unwrap().to_str().unwrap()
+                ))
+                .unwrap()
+                .parse()
+                .unwrap();
+                sectors.checked_mul(512).unwrap()
+            } else {
+                target_file.file.metadata().unwrap().len()
+            };
 
             let file_chunk_size = length.unwrap_or(1 * 1024 * 1024 * 1024); // 16GB
 
-            let mut chunk_count = file_size / file_chunk_size;
+            let mut chunk_count = file_size.checked_div(file_chunk_size).unwrap();
             let mut size_of_last_chunk = file_size % file_chunk_size;
 
             if size_of_last_chunk == 0 {