diff --git a/Cargo.toml b/Cargo.toml
index b1f9f0c..345b8f1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ resolver = "2"
 [workspace.package]
 version = "1.2.0"
 edition = "2024"
-rust-version = "1.85"
+rust-version = "1.98.1"
 license = "AGPL-3.0-only"
 
 [workspace.dependencies]
diff --git a/docs/development.md b/docs/development.md
index 2c8aa0b..8b7d277 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -2,7 +2,7 @@
 
 ## Building
 
-The pinned Rust toolchain is defined in `rust-toolchain.toml`. Build the CLI with `cargo build --release`; the binary is written to `target/release/senbei.exe` on Windows.
+Rust 1.98.1 is required and pinned in `rust-toolchain.toml`. Build the CLI with `cargo build --release`; the binary is written to `target/release/senbei.exe` on Windows.
 
 The workspace crates are portable where their APIs are pure. The browser binding is outside the workspace and is checked with `cargo check --manifest-path senbei-wasm/Cargo.toml` or built with `wasm-pack`.
 
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index f45a9a0..c08f3dd 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "stable"
+channel = "1.98.1"
 targets = ["x86_64-pc-windows-msvc", "wasm32-unknown-unknown"]
diff --git a/senbei-crypto/src/android/protector.rs b/senbei-crypto/src/android/protector.rs
index 2c962c7..8e5fb0a 100644
--- a/senbei-crypto/src/android/protector.rs
+++ b/senbei-crypto/src/android/protector.rs
@@ -552,7 +552,7 @@ pub fn transform_segment(
     let mut state = seed;
     let mut left = 0xe34e_ac63_u32;
     let mut right = 0x07b4_8238_u32;
-    for (index, chunk) in transformed.chunks_exact_mut(4).enumerate() {
+    for (index, chunk) in transformed.as_chunks_mut::<4>().0.iter_mut().enumerate() {
         let index32 = u32::try_from(index)
             .map_err(|_| Error::Invalid("segment word index exceeds u32".to_owned()))?;
         left = state
@@ -564,10 +564,7 @@ pub fn transform_segment(
             .wrapping_add(right.wrapping_sub(0x1605_a81c).wrapping_mul(right))
             .wrapping_shl(index32 & 7);
         state = left ^ right;
-        let bytes: [u8; 4] = chunk
-            .try_into()
-            .map_err(|_| Error::Invalid("invalid transformed word".to_owned()))?;
-        let mut value = u32::from_le_bytes(bytes);
+        let mut value = u32::from_le_bytes(*chunk);
         value = value.wrapping_add(0xb43b_9baf_u32.wrapping_mul(index32 & 0x0d));
         value ^= 0xaf57_f7fb_u32.wrapping_mul(index32 & 3);
         value = value.wrapping_sub(state) ^ state;
@@ -577,13 +574,10 @@ pub fn transform_segment(
     if decrypt_aes {
         let cipher = Aes256::new_from_slice(aes_key)
             .map_err(|_| Error::Invalid("invalid AES-256 key length".to_owned()))?;
-        let aligned_size = transformed.len() & !0x0f;
         let mut previous = [0_u8; 16];
-        for chunk in transformed[..aligned_size].chunks_exact_mut(16) {
-            let mut ciphertext = [0_u8; 16];
-            ciphertext.copy_from_slice(chunk);
-            // chunk is exactly one block (chunks_exact_mut(16)).
-            cipher.decrypt_block(chunk.try_into().expect("chunk is one block"));
+        for chunk in transformed.as_chunks_mut::<16>().0 {
+            let ciphertext = *chunk;
+            cipher.decrypt_block((&mut *chunk).into());
             for (byte, prior) in chunk.iter_mut().zip(previous) {
                 *byte ^= prior;
             }
diff --git a/senbei-engine/src/android/extract/stage1.rs b/senbei-engine/src/android/extract/stage1.rs
index 7e2ce5a..d18600d 100644
--- a/senbei-engine/src/android/extract/stage1.rs
+++ b/senbei-engine/src/android/extract/stage1.rs
@@ -177,18 +177,14 @@ fn decrypt_header(raw: &[u8], constant: u32) -> Result<Stage1Header> {
 }
 
 fn decrypt_words(ciphertext: &[u8], key: u32, constant: u32) -> Result<Vec<u8>> {
-    if ciphertext.len() % 4 != 0 {
+    if !ciphertext.len().is_multiple_of(4) {
         return invalid("Stage 1 word cipher input is not 4-byte aligned");
     }
     let mut plaintext = ciphertext.to_vec();
-    for (index, chunk) in plaintext.chunks_exact_mut(4).enumerate() {
+    for (index, chunk) in plaintext.as_chunks_mut::<4>().0.iter_mut().enumerate() {
         let index = u32::try_from(index)
             .map_err(|_| Error::Invalid("Stage 1 word index exceeds u32".to_owned()))?;
-        let mut word = u32::from_le_bytes(
-            chunk
-                .try_into()
-                .map_err(|_| Error::Invalid("Stage 1 word has an invalid size".to_owned()))?,
-        );
+        let mut word = u32::from_le_bytes(*chunk);
         word = word.wrapping_add(index.wrapping_add(3).wrapping_mul(key));
         word ^= constant.wrapping_mul(index.wrapping_add(1));
         chunk.copy_from_slice(&word.to_le_bytes());
diff --git a/senbei-engine/src/android/extract/stream.rs b/senbei-engine/src/android/extract/stream.rs
index f693442..6f87f59 100644
--- a/senbei-engine/src/android/extract/stream.rs
+++ b/senbei-engine/src/android/extract/stream.rs
@@ -130,13 +130,9 @@ fn decrypt_record(raw: &[u8], index: usize, state: u32) -> Result<Record> {
     let mut accumulator = 0x7993_4cf6_u32;
     let mut feedback = 0xf02f_7685_u32;
     let mut words = [0_u32; RECORD_SIZE / 4];
-    for (word_index, chunk) in raw.chunks_exact(4).enumerate() {
+    for (word_index, chunk) in raw.as_chunks::<4>().0.iter().enumerate() {
         feedback = feedback.wrapping_mul(feedback);
-        let cipher = u32::from_le_bytes(
-            chunk
-                .try_into()
-                .map_err(|_| Error::Invalid("record word has an invalid size".to_owned()))?,
-        );
+        let cipher = u32::from_le_bytes(*chunk);
         let mut value = gf32_mul_fixed(cipher ^ (feedback >> 3)) ^ index_mask;
         value = value.wrapping_add(accumulator).wrapping_add(state);
         value = value.wrapping_sub(mix >> ((word_index * 4 + 3) & 5));
diff --git a/senbei-engine/src/android/restore/pipeline.rs b/senbei-engine/src/android/restore/pipeline.rs
index 5cbcc96..482bdce 100644
--- a/senbei-engine/src/android/restore/pipeline.rs
+++ b/senbei-engine/src/android/restore/pipeline.rs
@@ -477,7 +477,8 @@ fn restore_hidden_symbols(
     dynstr: SectionHeader,
     patch_data: &[u8],
 ) -> Result<(Vec<u8>, Vec<u8>, HiddenSymbolReport)> {
-    if dynsym.entry_size != ELF64_SYMBOL_SIZE as u64 || dynsym.size % ELF64_SYMBOL_SIZE as u64 != 0
+    if dynsym.entry_size != ELF64_SYMBOL_SIZE as u64
+        || !dynsym.size.is_multiple_of(ELF64_SYMBOL_SIZE as u64)
     {
         return invalid("unexpected .dynsym entry layout");
     }
@@ -584,11 +585,13 @@ fn restore_hidden_symbols(
 }
 
 fn dynamic_symbol_names(symbols: &[u8], strings: &[u8]) -> Result<Vec<Vec<u8>>> {
-    if symbols.len() % ELF64_SYMBOL_SIZE != 0 {
+    if !symbols.len().is_multiple_of(ELF64_SYMBOL_SIZE) {
         return invalid("dynamic symbol table is not entry-aligned");
     }
     symbols
-        .chunks_exact(ELF64_SYMBOL_SIZE)
+        .as_chunks::<ELF64_SYMBOL_SIZE>()
+        .0
+        .iter()
         .map(|symbol| {
             let name_offset = read_u32(symbol, 0)? as usize;
             Ok(read_c_string(strings, name_offset, strings.len())?.to_vec())
@@ -698,7 +701,7 @@ fn patch_dynamic_tags(
     dynamic: SectionHeader,
     values: &BTreeMap<u64, u64>,
 ) -> Result<()> {
-    if dynamic.size % 0x10 != 0 {
+    if !dynamic.size.is_multiple_of(0x10) {
         return invalid(".dynamic size is not entry-aligned");
     }
     let start = usize_from_u64(dynamic.offset, ".dynamic offset")?;
@@ -732,7 +735,7 @@ fn patch_dynamic_tags(
 }
 
 fn dynamic_contains_tag(output: &[u8], dynamic: SectionHeader, wanted: u64) -> Result<bool> {
-    if dynamic.size % 0x10 != 0 {
+    if !dynamic.size.is_multiple_of(0x10) {
         return invalid(".dynamic size is not entry-aligned");
     }
     let start = usize_from_u64(dynamic.offset, ".dynamic offset")?;
@@ -1418,13 +1421,12 @@ fn validate_restored_binary(
         rela_plt.size / ELF64_RELA_SIZE as u64,
         "restored PLT relocation count",
     )?;
-    if let Some(expected) = materialization {
-        if dynamic_symbols != expected.new_symbol_count
+    if let Some(expected) = materialization
+        && (dynamic_symbols != expected.new_symbol_count
             || dynamic_relocations != expected.rela_dyn_count
-            || pltgot_relocations != expected.rela_plt_count
-        {
-            return invalid("restored ELF table counts do not match materialization report");
-        }
+            || pltgot_relocations != expected.rela_plt_count)
+    {
+        return invalid("restored ELF table counts do not match materialization report");
     }
     Ok(ValidationReport {
         format: "ELF64".to_owned(),
diff --git a/senbei-engine/src/windows/exe/pipeline.rs b/senbei-engine/src/windows/exe/pipeline.rs
index 24eca20..3b7b702 100644
--- a/senbei-engine/src/windows/exe/pipeline.rs
+++ b/senbei-engine/src/windows/exe/pipeline.rs
@@ -396,7 +396,7 @@ impl<'a> Unpacker<'a> {
                 // non-critical for false-positive rejection.
                 if v8 < info6 {
                     let delta = info6.wrapping_sub(v8);
-                    if delta <= 0x1000 && delta % 0x200 == 0 {
+                    if delta <= 0x1000 && delta.is_multiple_of(0x200) {
                         anchor = Some(probe);
                         break;
                     }
diff --git a/senbei-wasm/Cargo.toml b/senbei-wasm/Cargo.toml
index d296dc9..3f02557 100644
--- a/senbei-wasm/Cargo.toml
+++ b/senbei-wasm/Cargo.toml
@@ -2,6 +2,7 @@
 name = "senbei-wasm"
 version = "1.2.0"
 edition = "2024"
+rust-version = "1.98.1"
 description = "WebAssembly bindings for senbei (browser frontend assets live in web/)"
 license = "AGPL-3.0-only"