diff --git a/libbz2-rs-sys/src/allocator.rs b/libbz2-rs-sys/src/allocator.rs
index 1347a822d..8828896fd 100644
--- a/libbz2-rs-sys/src/allocator.rs
+++ b/libbz2-rs-sys/src/allocator.rs
@@ -106,7 +106,20 @@ pub(crate) mod c_allocator {
     pub(crate) static ALLOCATOR: (AllocFunc, FreeFunc) = (self::allocate, self::deallocate);
 
     unsafe extern "C" fn allocate(_opaque: *mut c_void, count: c_int, size: c_int) -> *mut c_void {
-        unsafe { libc::malloc((count * size) as usize) }
+        // NOTE: allocations bigger than isize::MAX are UB in LLVM.
+        let (Ok(count), Ok(size)) = (isize::try_from(count), isize::try_from(size)) else {
+            return core::ptr::null_mut();
+        };
+
+        let Some(len) = count.checked_mul(size) else {
+            return core::ptr::null_mut();
+        };
+
+        let Ok(len) = usize::try_from(len) else {
+            return core::ptr::null_mut();
+        };
+
+        unsafe { libc::malloc(len) }
     }
 
     unsafe extern "C" fn deallocate(_opaque: *mut c_void, ptr: *mut c_void) {
diff --git a/libbz2-rs-sys/src/bzlib.rs b/libbz2-rs-sys/src/bzlib.rs
index 59b6fa4de..3c22f6ed3 100644
--- a/libbz2-rs-sys/src/bzlib.rs
+++ b/libbz2-rs-sys/src/bzlib.rs
@@ -87,7 +87,7 @@ macro_rules! prefix {
 
 pub(crate) use prefix;
 
-/// The version of the zlib library.
+/// The version of the libbzip2-rs-sys library.
 ///
 /// Its value is a pointer to a NULL-terminated sequence of bytes.
 ///
@@ -95,8 +95,8 @@ pub(crate) use prefix;
 #[doc = libbz2_rs_sys_version!()]
 /// `:
 ///
-/// - The first component is the version of stock zlib that this release is compatible with
-/// - The final component is the zlib-rs version used to build this release.
+/// - The first component is the version of stock bzip2 that this release is compatible with
+/// - The final component is the libbzip2-rs-sys version used to build this release.
 #[cfg_attr(feature = "export-symbols", export_name = prefix!(BZ2_bzlibVersion))]
 #[cfg(feature = "stdio")]
 pub const extern "C" fn BZ2_bzlibVersion() -> *const core::ffi::c_char {
@@ -1058,7 +1058,7 @@ impl TryFrom<i32> for Action {
 ///     - after [`BZ2_bzCompressEnd`]
 /// - [`BZ_PARAM_ERROR`] if any of
 ///     - `strm.is_null()`
-///     - `strm.s.is_null()`
+///     - `strm.state.is_null()`
 ///     - action is not one of [`BZ_RUN`], [`BZ_FLUSH`] or [`BZ_FINISH`]
 /// - [`BZ_RUN_OK`] successfully compressed, but ran out of input or output space
 /// - [`BZ_FLUSH_OK`] not all compressed data has been written to the output yet
@@ -1173,7 +1173,7 @@ fn compress_loop(strm: &mut BzStream<EState>, s: &mut EState, action: i32) -> Re
 ///
 /// - [`BZ_PARAM_ERROR`] if any of
 ///     - `strm.is_null()`
-///     - `strm.s.is_null()`
+///     - `strm.state.is_null()`
 ///     - no [valid allocator](bz_stream#custom-allocators) could be configured
 /// - [`BZ_OK`] otherwise
 ///
@@ -1596,7 +1596,7 @@ pub(crate) fn index_into_f(index: u32, cftab: &[u32; 257]) -> u8 {
 
 macro_rules! GET_LL4 {
     ($s:expr, $i:expr) => {
-        $s.ll4.as_slice()[($s.tPos >> 1) as usize] as u32 >> ($s.tPos << 2 & 0x4) & 0xf
+        $s.ll4.as_slice()[($s.tPos >> 1) as usize] as u32 >> ($i << 2 & 0x4) & 0xf
     };
 }
 
@@ -1766,7 +1766,7 @@ fn un_rle_obuf_to_output_small(strm: &mut BzStream<DState>, s: &mut DState) -> b
 ///
 /// - [`BZ_PARAM_ERROR`] if any of
 ///     - `strm.is_null()`
-///     - `strm.s.is_null()`
+///     - `strm.state.is_null()`
 ///     - `strm.avail_out < 1`
 /// - [`BZ_DATA_ERROR`] if a data integrity error is detected in the compressed stream
 /// - [`BZ_DATA_ERROR_MAGIC`] if the compressed stream doesn't begin with the right magic bytes
@@ -1879,7 +1879,7 @@ pub(crate) fn BZ2_bzDecompressHelp(strm: &mut BzStream<DState>) -> ReturnCode {
 ///
 /// - [`BZ_PARAM_ERROR`] if any of
 ///     - `strm.is_null()`
-///     - `strm.s.is_null()`
+///     - `strm.state.is_null()`
 ///     - no [valid allocator](bz_stream#custom-allocators) could be configured
 /// - [`BZ_OK`] otherwise
 ///