diff --git a/crates/fspy/src/lib.rs b/crates/fspy/src/lib.rs
index 13ff2055b..6c89414ba 100644
--- a/crates/fspy/src/lib.rs
+++ b/crates/fspy/src/lib.rs
@@ -1,5 +1,4 @@
 #![cfg_attr(target_os = "windows", feature(windows_process_extensions_main_thread_handle))]
-#![feature(once_cell_try)]
 
 pub mod error;
 
diff --git a/crates/fspy_preload_unix/src/interceptions/linux_syscall.rs b/crates/fspy_preload_unix/src/interceptions/linux_syscall.rs
index f368a8380..e4d9603ec 100644
--- a/crates/fspy_preload_unix/src/interceptions/linux_syscall.rs
+++ b/crates/fspy_preload_unix/src/interceptions/linux_syscall.rs
@@ -10,17 +10,17 @@ intercept!(syscall(64): unsafe extern "C" fn(c_long, args: ...) -> c_long);
 unsafe extern "C" fn syscall(syscall_no: c_long, mut args: ...) -> c_long {
     // https://github.com/bminor/glibc/blob/efc8642051e6c4fe5165e8986c1338ba2c180de6/sysdeps/unix/sysv/linux/syscall.c#L23
     // SAFETY: extracting variadic arguments matching the syscall ABI; the caller passes at least 6 c_long arguments
-    let a0 = unsafe { args.arg::<c_long>() };
+    let a0 = unsafe { args.next_arg::<c_long>() };
     // SAFETY: extracting variadic arguments matching the syscall ABI
-    let a1 = unsafe { args.arg::<c_long>() };
+    let a1 = unsafe { args.next_arg::<c_long>() };
     // SAFETY: extracting variadic arguments matching the syscall ABI
-    let a2 = unsafe { args.arg::<c_long>() };
+    let a2 = unsafe { args.next_arg::<c_long>() };
     // SAFETY: extracting variadic arguments matching the syscall ABI
-    let a3 = unsafe { args.arg::<c_long>() };
+    let a3 = unsafe { args.next_arg::<c_long>() };
     // SAFETY: extracting variadic arguments matching the syscall ABI
-    let a4 = unsafe { args.arg::<c_long>() };
+    let a4 = unsafe { args.next_arg::<c_long>() };
     // SAFETY: extracting variadic arguments matching the syscall ABI
-    let a5 = unsafe { args.arg::<c_long>() };
+    let a5 = unsafe { args.next_arg::<c_long>() };
 
     if syscall_no == libc::SYS_statx {
         // c-style conversion is expected: (4294967196 -> -100 aka libc::AT_FDCWD)
diff --git a/crates/fspy_preload_unix/src/interceptions/open.rs b/crates/fspy_preload_unix/src/interceptions/open.rs
index 41c5d6537..8dca5b48f 100644
--- a/crates/fspy_preload_unix/src/interceptions/open.rs
+++ b/crates/fspy_preload_unix/src/interceptions/open.rs
@@ -31,7 +31,7 @@ unsafe extern "C" fn open(path: *const c_char, flags: c_int, mut args: ...) -> c
     unsafe { handle_open(path, OpenFlags(flags)) };
     if has_mode_arg(flags) {
         // SAFETY: when O_CREAT or O_TMPFILE is set, a mode_t argument is required by the open() contract
-        let mode: Mode = unsafe { args.arg() };
+        let mode: Mode = unsafe { args.next_arg() };
         // SAFETY: calling the original libc open() with the same arguments forwarded from the interposed function
         unsafe { open::original()(path, flags, mode) }
     } else {
@@ -53,7 +53,7 @@ unsafe extern "C" fn openat(
     if has_mode_arg(flags) {
         // https://github.com/tailhook/openat/issues/21#issuecomment-535914957
         // SAFETY: when O_CREAT or O_TMPFILE is set, a mode_t argument is required by the openat() contract
-        let mode: Mode = unsafe { args.arg() };
+        let mode: Mode = unsafe { args.next_arg() };
         // SAFETY: calling the original libc openat() with the same arguments forwarded from the interposed function
         unsafe { openat::original()(dirfd, path, flags, mode) }
     } else {
diff --git a/crates/fspy_preload_unix/src/interceptions/spawn/exec/mod.rs b/crates/fspy_preload_unix/src/interceptions/spawn/exec/mod.rs
index 09d7b7bca..182226eea 100644
--- a/crates/fspy_preload_unix/src/interceptions/spawn/exec/mod.rs
+++ b/crates/fspy_preload_unix/src/interceptions/spawn/exec/mod.rs
@@ -111,7 +111,7 @@ unsafe extern "C" fn execle(path: *const c_char, arg0: *const c_char, valist: ..
     // SAFETY: valist and arg0 are valid variadic arguments forwarded from the interposed execle function
     unsafe {
         with_argv(valist, arg0, |args, mut remaining| {
-            let envp = remaining.arg::<*const *const c_char>();
+            let envp = remaining.next_arg::<*const *const c_char>();
             handle_exec(ExecResolveConfig::search_path_disabled(), path, args.as_ptr(), envp)
         })
     }
diff --git a/crates/fspy_preload_unix/src/interceptions/spawn/exec/with_argv.rs b/crates/fspy_preload_unix/src/interceptions/spawn/exec/with_argv.rs
index e5d41d06f..c3aba13ea 100644
--- a/crates/fspy_preload_unix/src/interceptions/spawn/exec/with_argv.rs
+++ b/crates/fspy_preload_unix/src/interceptions/spawn/exec/with_argv.rs
@@ -17,7 +17,7 @@ pub unsafe fn with_argv(
     let argc = 1 + {
         let mut va = va.clone();
         // Safety: argv is guaranteed to be NULL-terminated
-        core::iter::from_fn(|| Some(unsafe { va.arg::<*const c_char>() }))
+        core::iter::from_fn(|| Some(unsafe { va.next_arg::<*const c_char>() }))
             .position(|s| {
                 // Find the NULL terminator
                 s.is_null()
@@ -47,11 +47,11 @@ pub unsafe fn with_argv(
 
     for item in out.iter_mut().take(argc).skip(1) {
         // SAFETY: extracting the next *const c_char argument from the va_list; the count was pre-validated
-        item.write(unsafe { va.arg::<*const c_char>() });
+        item.write(unsafe { va.next_arg::<*const c_char>() });
     }
     out[argc].write(core::ptr::null());
     // SAFETY: consuming the NULL terminator from the va_list to advance past it
-    unsafe { va.arg::<*const c_char>() };
+    unsafe { va.next_arg::<*const c_char>() };
 
     // Safety: MaybeUninit<*const c_char> has the same layout as *const c_char,
     // and all elements have been initialized via write() above.
diff --git a/crates/fspy_seccomp_unotify/src/supervisor/handler/arg.rs b/crates/fspy_seccomp_unotify/src/supervisor/handler/arg.rs
index 61fd353d1..fa9dc305d 100644
--- a/crates/fspy_seccomp_unotify/src/supervisor/handler/arg.rs
+++ b/crates/fspy_seccomp_unotify/src/supervisor/handler/arg.rs
@@ -155,7 +155,6 @@ impl Fd {
 }
 
 impl FromSyscallArg for Fd {
-    #[expect(clippy::cast_possible_truncation, reason = "syscall arg represents a file descriptor")]
     fn from_syscall_arg(arg: u64) -> io::Result<Self> {
         Ok(Self { fd: arg as RawFd })
     }
diff --git a/crates/fspy_seccomp_unotify/tests/arg_types.rs b/crates/fspy_seccomp_unotify/tests/arg_types.rs
index 810dd478a..93c1c9740 100644
--- a/crates/fspy_seccomp_unotify/tests/arg_types.rs
+++ b/crates/fspy_seccomp_unotify/tests/arg_types.rs
@@ -110,7 +110,7 @@ async fn fd_and_path() -> Result<(), Box<dyn Error>> {
 
 #[tokio::test]
 async fn path_long() -> Result<(), Box<dyn Error>> {
-    let long_path = [b'a'].repeat(30000);
+    let long_path = b"a".repeat(30000);
     let long_path_cstr = CString::new(long_path.as_slice()).unwrap();
     let syscalls = run_in_pre_exec(move || {
         let _ = openat(AT_FDCWD, long_path_cstr.as_c_str(), OFlag::O_RDONLY, Mode::empty());
@@ -129,7 +129,7 @@ async fn path_long() -> Result<(), Box<dyn Error>> {
 
 #[tokio::test]
 async fn path_overflow() -> Result<(), Box<dyn Error>> {
-    let long_path = [b'a'].repeat(40000);
+    let long_path = b"a".repeat(40000);
     let long_path_cstr = CString::new(long_path.as_slice()).unwrap();
     let syscalls = run_in_pre_exec(move || {
         let _ = openat(AT_FDCWD, long_path_cstr.as_c_str(), OFlag::O_RDONLY, Mode::empty());
diff --git a/crates/preload_test_lib/src/lib.rs b/crates/preload_test_lib/src/lib.rs
index b3be39765..6b6dbdc9c 100644
--- a/crates/preload_test_lib/src/lib.rs
+++ b/crates/preload_test_lib/src/lib.rs
@@ -84,7 +84,7 @@ pub unsafe extern "C" fn open(path: *const c_char, flags: c_int, mut args: ...)
     if has_mode_arg(flags) {
         // SAFETY: `O_CREAT`/`O_TMPFILE` guarantees a `mode_t` follows per
         // the `open(2)` contract.
-        let mode: libc::mode_t = unsafe { args.arg() };
+        let mode: libc::mode_t = unsafe { args.next_arg() };
         // SAFETY: forwarding the caller's arguments unchanged.
         unsafe { next_open()(path, flags, mode) }
     } else {
@@ -103,7 +103,7 @@ pub unsafe extern "C" fn open64(path: *const c_char, flags: c_int, mut args: ...
     if has_mode_arg(flags) {
         // SAFETY: `O_CREAT`/`O_TMPFILE` guarantees a `mode_t` follows per
         // the `open64(2)` contract.
-        let mode: libc::mode_t = unsafe { args.arg() };
+        let mode: libc::mode_t = unsafe { args.next_arg() };
         // SAFETY: forwarding the caller's arguments unchanged.
         unsafe { next_open64()(path, flags, mode) }
     } else {
@@ -127,7 +127,7 @@ pub unsafe extern "C" fn openat(
     if has_mode_arg(flags) {
         // SAFETY: `O_CREAT`/`O_TMPFILE` guarantees a `mode_t` follows per
         // the `openat(2)` contract.
-        let mode: libc::mode_t = unsafe { args.arg() };
+        let mode: libc::mode_t = unsafe { args.next_arg() };
         // SAFETY: forwarding the caller's arguments unchanged.
         unsafe { next_openat()(dirfd, path, flags, mode) }
     } else {
@@ -151,7 +151,7 @@ pub unsafe extern "C" fn openat64(
     if has_mode_arg(flags) {
         // SAFETY: `O_CREAT`/`O_TMPFILE` guarantees a `mode_t` follows per
         // the `openat64(2)` contract.
-        let mode: libc::mode_t = unsafe { args.arg() };
+        let mode: libc::mode_t = unsafe { args.next_arg() };
         // SAFETY: forwarding the caller's arguments unchanged.
         unsafe { next_openat64()(dirfd, path, flags, mode) }
     } else {
diff --git a/crates/pty_terminal/tests/terminal.rs b/crates/pty_terminal/tests/terminal.rs
index 33755024d..17bf0f7ac 100644
--- a/crates/pty_terminal/tests/terminal.rs
+++ b/crates/pty_terminal/tests/terminal.rs
@@ -243,7 +243,7 @@ fn resize_terminal() {
         stdout().flush().unwrap();
     }));
 
-    let Terminal { mut pty_reader, mut pty_writer, child_handle: _, .. } =
+    let Terminal { mut pty_reader, mut pty_writer, .. } =
         Terminal::spawn(ScreenSize { rows: 80, cols: 80 }, cmd).unwrap();
 
     // Wait for initial size line (synchronize before resizing)
@@ -349,7 +349,7 @@ fn send_ctrl_c_interrupts_process() {
         }
     }));
 
-    let Terminal { mut pty_reader, mut pty_writer, child_handle: _, .. } =
+    let Terminal { mut pty_reader, mut pty_writer, .. } =
         Terminal::spawn(ScreenSize { rows: 80, cols: 80 }, cmd).unwrap();
 
     // Wait for process to be ready
diff --git a/crates/vite_path/src/absolute/mod.rs b/crates/vite_path/src/absolute/mod.rs
index 4ecc4f44d..3bb1f4104 100644
--- a/crates/vite_path/src/absolute/mod.rs
+++ b/crates/vite_path/src/absolute/mod.rs
@@ -233,7 +233,7 @@ impl Display for StripPrefixError<'_> {
         f.write_fmt(format_args!(
             "{}: {}",
             self.stripped_path.display(),
-            &self.invalid_path_data_error
+            self.invalid_path_data_error
         ))
     }
 }
diff --git a/crates/vite_task/src/session/cache/mod.rs b/crates/vite_task/src/session/cache/mod.rs
index f310ddc00..6a25846c8 100644
--- a/crates/vite_task/src/session/cache/mod.rs
+++ b/crates/vite_task/src/session/cache/mod.rs
@@ -300,7 +300,7 @@ impl ExecutionCache {
             } else if old_input_config != cache_metadata.input_config {
                 FingerprintMismatch::InputConfig
             } else {
-                debug_assert!(old_output_config != cache_metadata.output_config);
+                debug_assert_ne!(old_output_config, cache_metadata.output_config);
                 FingerprintMismatch::OutputConfig
             };
             return Ok(Err(CacheMiss::FingerprintMismatch(mismatch)));
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 0c9510993..28f78048d 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -2,5 +2,5 @@
 # Needed nightly features:
 # - cargo `Z-bindeps` to build and embed preload shared libraries as dependencies of fspy
 # - `windows_process_extensions_main_thread_handle` to get the main thread handle for Detours injection
-channel = "nightly-2026-03-05"
+channel = "nightly-2026-05-24"
 profile = "default"