diff --git a/src/error.rs b/src/error.rs
index 7c3a8f9..0c5b8be 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -6,7 +6,7 @@ use std::io;
 pub enum Error {
     BadMagic(u16),
     OutOfBounds(usize),
-    AddressOutOfBounds(usize, usize, usize),
+    AddressOutOfBounds(u32, u32, usize),
     BadBlockGroupCount(u32, u32),
     #[cfg(any(test, not(feature = "no_std")))]
     Io(io::Error),
diff --git a/src/fs.rs b/src/fs.rs
index ef40187..385765a 100644
--- a/src/fs.rs
+++ b/src/fs.rs
@@ -37,7 +37,7 @@ where
     pub fn new(volume: V) -> Result<Ext2<S, V>, Error> {
         let superblock = unsafe { Struct::from(Superblock::find(&volume)?) };
         let block_groups_offset = Address::with_block_size(
-            superblock.inner.first_data_block as usize + 1,
+            superblock.inner.first_data_block + 1,
             0,
             superblock.inner.log_block_size + 10,
         );
@@ -237,12 +237,11 @@ where
             let index = (self.index - 1) % self.inodes_per_group;
             self.index += 1;
 
-            let inodes_block =
-                self.block_groups[block_group].inode_table_block as usize;
+            let inodes_block = self.block_groups[block_group].inode_table_block;
 
             let offset = Address::with_block_size(
                 inodes_block,
-                (index * self.inode_size) as isize,
+                (index * self.inode_size) as i32,
                 self.log_block_size,
             );
             let raw = unsafe {
@@ -267,7 +266,7 @@ impl<'a, S: 'a + Size + Copy, V: 'a + Volume<u8, Address<S>>> Inode<'a, S, V> {
         Inode { fs, inner }
     }
 
-    pub fn block(&self, index: usize) -> Option<NonZero<usize>> {
+    pub fn block(&self, index: usize) -> Option<NonZero<u32>> {
         // number of blocks in direct table: 12
         // number of blocks in indirect table: block_size/4
         //   why?
@@ -284,19 +283,19 @@ impl<'a, S: 'a + Size + Copy, V: 'a + Volume<u8, Address<S>>> Inode<'a, S, V> {
 
         let bs4 = self.fs.block_size() / 4;
         if index < 12 {
-            NonZero::new(self.inner.direct_pointer[index] as usize)
+            NonZero::new(self.inner.direct_pointer[index])
         } else if index < bs4 + 12 {
-            let block = self.inner.indirect_pointer as usize;
+            let block = self.inner.indirect_pointer;
             let offset = index - 12;
             let addr = Address::with_block_size(
                 block,
-                offset as isize,
+                offset as i32,
                 self.fs.log_block_size(),
             );
-            let size = Address::from(4_usize);
+            let size = Address::from(4_u64);
             let slice = self.fs.volume.slice(addr..addr + size);
             slice.and_then(|slice| unsafe {
-                NonZero::new(u32::from_le(slice.dynamic_cast::<u32>().0) as usize)
+                NonZero::new(u32::from_le(slice.dynamic_cast::<u32>().0))
             })
         } else if index < bs4 * bs4 + bs4 + 12 {
             unimplemented!("doubly indirect pointer table");
@@ -405,15 +404,15 @@ mod tests {
     fn file_len() {
         let file = RefCell::new(File::open("ext2.img").unwrap());
         assert_eq!(
-            Address::<Size512>::from(2048_usize)
-                - Address::<Size512>::from(1024_usize),
+            Address::<Size512>::from(2048_u64)
+                - Address::<Size512>::from(1024_u64),
             Address::<Size512>::new(2, 0)
         );
         assert_eq!(
             unsafe {
                 file.slice_unchecked(
-                    Address::<Size512>::from(1024_usize)
-                        ..Address::<Size512>::from(2048_usize),
+                    Address::<Size512>::from(1024_u64)
+                        ..Address::<Size512>::from(2048_u64),
                 ).len()
             },
             1024
diff --git a/src/sector.rs b/src/sector.rs
index 85c4e63..de229fd 100644
--- a/src/sector.rs
+++ b/src/sector.rs
@@ -8,7 +8,7 @@ pub trait Size: PartialOrd {
     // log_sector_size = log_2(sector_size)
     const LOG_SIZE: u32;
     const SIZE: usize = 1 << Self::LOG_SIZE;
-    const OFFSET_MASK: usize = Self::SIZE - 1;
+    const OFFSET_MASK: u32 = (Self::SIZE - 1) as u32;
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
@@ -38,14 +38,14 @@ impl Size for Size4096 {
 /// Address in a physical sector
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 pub struct Address<S: Size> {
-    sector: usize,
-    offset: usize,
+    sector: u32,
+    offset: u32,
     _phantom: PhantomData<S>,
 }
 
 impl<S: Size> Address<S> {
-    pub unsafe fn new_unchecked(sector: usize, offset: usize) -> Address<S> {
-        assert!(offset < S::SIZE, "offset out of sector bounds");
+    pub unsafe fn new_unchecked(sector: u32, offset: u32) -> Address<S> {
+        assert!((offset as usize) < S::SIZE, "offset out of sector bounds");
         let _phantom = PhantomData;
         Address {
             sector,
@@ -54,37 +54,31 @@ impl<S: Size> Address<S> {
         }
     }
 
-    pub fn new(sector: usize, offset: isize) -> Address<S> {
-        let sector = (sector as isize + (offset >> S::LOG_SIZE)) as usize;
-        let offset = offset.abs() as usize & S::OFFSET_MASK;
+    pub fn new(sector: u32, offset: i32) -> Address<S> {
+        let sector = (sector as i32 + (offset >> S::LOG_SIZE)) as u32;
+        let offset = offset.abs() as u32 & S::OFFSET_MASK;
         unsafe { Address::new_unchecked(sector, offset) }
     }
 
     pub fn with_block_size(
-        block: usize,
-        offset: isize,
+        block: u32,
+        offset: i32,
         log_block_size: u32,
     ) -> Address<S> {
-        let block = (block as isize + (offset >> log_block_size)) as usize;
-        let offset = offset.abs() as usize & ((1 << log_block_size) - 1);
+        let block = (block as i32 + (offset >> log_block_size)) as u32;
+        let offset = offset.abs() as u32 & ((1 << log_block_size) - 1);
 
-        let log_diff = log_block_size as isize - S::LOG_SIZE as isize;
+        let log_diff = log_block_size as i32 - S::LOG_SIZE as i32;
         let top_offset = offset >> S::LOG_SIZE;
         let offset = offset & ((1 << S::LOG_SIZE) - 1);
         let sector = block << log_diff | top_offset;
         unsafe { Address::new_unchecked(sector, offset) }
     }
 
-    pub fn index64(&self) -> u64 {
+    pub fn into_index(&self) -> u64 {
         ((self.sector as u64) << S::LOG_SIZE) + self.offset as u64
     }
 
-    pub fn into_index(&self) -> Option<usize> {
-        self.sector
-            .checked_shl(S::LOG_SIZE)
-            .and_then(|sector| sector.checked_add(self.offset))
-    }
-
     pub const fn sector_size(&self) -> usize {
         S::SIZE
     }
@@ -93,11 +87,11 @@ impl<S: Size> Address<S> {
         S::LOG_SIZE
     }
 
-    pub fn sector(&self) -> usize {
+    pub fn sector(&self) -> u32 {
         self.sector
     }
 
-    pub fn offset(&self) -> usize {
+    pub fn offset(&self) -> u32 {
         self.offset
     }
 }
@@ -105,7 +99,7 @@ impl<S: Size> Address<S> {
 impl<S: Size + Clone + PartialOrd> Step for Address<S> {
     fn steps_between(start: &Self, end: &Self) -> Option<usize> {
         if end.sector >= start.sector {
-            Some(end.sector - start.sector)
+            Some(end.sector as usize - start.sector as usize)
         } else {
             None
         }
@@ -129,7 +123,7 @@ impl<S: Size + Clone + PartialOrd> Step for Address<S> {
 
     fn add_usize(&self, n: usize) -> Option<Self> {
         self.sector
-            .checked_add(n)
+            .checked_add(n as u32)
             .map(|sector| Address::new(sector, 0))
     }
 }
@@ -160,15 +154,15 @@ impl<S: Size> From<u64> for Address<S> {
     fn from(idx: u64) -> Address<S> {
         let sector = idx >> S::LOG_SIZE;
         let offset = idx & S::OFFSET_MASK as u64;
-        Address::new(sector as usize, offset as isize)
+        Address::new(sector as u32, offset as i32)
     }
 }
 
 impl<S: Size> From<usize> for Address<S> {
     fn from(idx: usize) -> Address<S> {
         let sector = idx >> S::LOG_SIZE;
-        let offset = idx & S::OFFSET_MASK;
-        Address::new(sector, offset as isize)
+        let offset = idx & S::OFFSET_MASK as usize;
+        Address::new(sector as u32, offset as i32)
     }
 }
 
@@ -177,7 +171,7 @@ impl<S: Size> Add for Address<S> {
     fn add(self, rhs: Address<S>) -> Address<S> {
         Address::new(
             self.sector + rhs.sector,
-            (self.offset + rhs.offset) as isize,
+            (self.offset + rhs.offset) as i32,
         )
     }
 }
@@ -187,7 +181,7 @@ impl<S: Size> Sub for Address<S> {
     fn sub(self, rhs: Address<S>) -> Address<S> {
         Address::new(
             self.sector - rhs.sector,
-            self.offset as isize - rhs.offset as isize,
+            self.offset as i32 - rhs.offset as i32,
         )
     }
 }
@@ -198,22 +192,19 @@ mod tests {
 
     #[test]
     fn conv() {
-        assert_eq!(Address::<Size512>::new(0, 1024).into_index(), Some(1024));
-        assert_eq!(
-            Address::<Size512>::from(1024_usize).into_index(),
-            Some(1024)
-        );
+        assert_eq!(Address::<Size512>::new(0, 1024).into_index(), 1024);
+        assert_eq!(Address::<Size512>::from(1024_u64).into_index(), 1024);
         assert_eq!(
             Address::<Size512>::with_block_size(1, 256, 10).into_index(),
-            Some(1024 + 256)
+            1024 + 256
         );
         assert_eq!(
             Address::<Size512>::with_block_size(2, 0, 10).into_index(),
-            Some(2048)
+            2048
         );
         assert_eq!(
             Address::<Size512>::with_block_size(0, 1792, 10).into_index(),
-            Some(1792)
+            1792
         );
     }
 
@@ -232,11 +223,11 @@ mod tests {
         let a = Address::<Size2048>::new(0, 1024);
         let b = Address::<Size2048>::new(0, 1024);
         assert_eq!(a + b, Address::<Size2048>::new(1, 0));
-        assert_eq!((a + b).into_index(), Some(2048));
+        assert_eq!((a + b).into_index(), 2048);
 
         let a = Address::<Size512>::new(0, 2048);
         let b = Address::<Size512>::new(0, 256);
         assert_eq!(a - b, Address::<Size512>::new(3, 256));
-        assert_eq!((a - b).into_index(), Some(1792));
+        assert_eq!((a - b).into_index(), 1792);
     }
 }
diff --git a/src/volume/mod.rs b/src/volume/mod.rs
index 1103013..054dd37 100644
--- a/src/volume/mod.rs
+++ b/src/volume/mod.rs
@@ -246,7 +246,7 @@ macro_rules! impl_slice {
                 slice: Option<VolumeCommit<T, Address<S>>>,
             ) -> Result<(), Infallible> {
                 slice.map(|slice| {
-                    let index = slice.at_index().index64() as usize;
+                    let index = slice.at_index().into_index() as usize;
                     let end = index + slice.as_ref().len();
                     // XXX: it would be much better to drop the contents of dst
                     // and move the contents of slice instead of cloning
@@ -262,8 +262,8 @@ macro_rules! impl_slice {
                 range: Range<Address<S>>,
             ) -> VolumeSlice<'a, T, Address<S>> {
                 let index = range.start;
-                let range = range.start.index64() as usize
-                    ..range.end.index64() as usize;
+                let range = range.start.into_index() as usize
+                    ..range.end.into_index() as usize;
                 VolumeSlice::new(
                     <Self as AsRef<[T]>>::as_ref(self).get_unchecked(range),
                     index,
@@ -303,7 +303,7 @@ mod file {
                 self.borrow()
                     .metadata()
                     .map(|data| Address::from(data.len()))
-                    .unwrap_or(Address::from(0_usize)),
+                    .unwrap_or(Address::new(0, 0)),
             )
         }
 
@@ -316,7 +316,7 @@ mod file {
                     let index = *slice.at_index();
                     let mut refmut = self.borrow_mut();
                     refmut
-                        .seek(SeekFrom::Start(index.index64()))
+                        .seek(SeekFrom::Start(index.into_index()))
                         .and_then(|_| refmut.write(slice.as_ref()))
                         .map(|_| ())
                 })
@@ -329,11 +329,11 @@ mod file {
         ) -> VolumeSlice<'a, u8, Address<S>> {
             let index = range.start;
             let len = range.end - range.start;
-            let mut vec = Vec::with_capacity(len.index64() as usize);
-            vec.set_len(len.index64() as usize);
+            let mut vec = Vec::with_capacity(len.into_index() as usize);
+            vec.set_len(len.into_index() as usize);
             let mut refmut = self.borrow_mut();
             refmut
-                .seek(SeekFrom::Start(index.index64()))
+                .seek(SeekFrom::Start(index.into_index()))
                 .and_then(|_| refmut.read_exact(&mut vec[..]))
                 .unwrap_or_else(|err| {
                     panic!("could't read from File Volume: {:?}", err)
@@ -346,15 +346,15 @@ mod file {
             range: Range<Address<S>>,
         ) -> Option<VolumeSlice<'a, u8, Address<S>>> {
             let index = range.start;
-            let mut vec = Vec::with_capacity(
-                (range.end - range.start).index64() as usize,
-            );
+            let mut vec = Vec::with_capacity((range.end - range.start)
+                .into_index()
+                as usize);
             unsafe {
-                vec.set_len((range.end - range.start).index64() as usize);
+                vec.set_len((range.end - range.start).into_index() as usize);
             }
             let mut refmut = self.borrow_mut();
             refmut
-                .seek(SeekFrom::Start(index.index64()))
+                .seek(SeekFrom::Start(index.into_index()))
                 .and_then(|_| refmut.read_exact(&mut vec[..]))
                 .map(move |_| VolumeSlice::new_owned(vec, index))
                 .ok()
@@ -373,8 +373,8 @@ mod tests {
         let commit = {
             let mut slice = volume
                 .slice(
-                    Address::<Size512>::from(256_usize)
-                        ..Address::<Size512>::from(512_usize),
+                    Address::<Size512>::from(256_u64)
+                        ..Address::<Size512>::from(512_u64),
                 )
                 .unwrap();
             slice.iter_mut().for_each(|x| *x = 1);