diff --git a/.github/workflows/ctutils.yml b/.github/workflows/ctutils.yml
index 997b3a07..cc8633dc 100644
--- a/.github/workflows/ctutils.yml
+++ b/.github/workflows/ctutils.yml
@@ -48,6 +48,15 @@ jobs:
       - run: cargo build --target ${{ matrix.target }}
       - run: cargo build --target ${{ matrix.target }} --features alloc
 
+  checkct:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: Ledger-Donjon/cargo-checkct@85271e5ce9eab9ba895c62c8b5d4129810a635a0
+        with:
+          directory: ctutils
+          timeout: 120
+
   minimal-versions:
     uses: RustCrypto/actions/.github/workflows/minimal-versions.yml@master
     with:
diff --git a/ctutils/checkct/.cargo/config.toml b/ctutils/checkct/.cargo/config.toml
new file mode 100644
index 00000000..aeb3543b
--- /dev/null
+++ b/ctutils/checkct/.cargo/config.toml
@@ -0,0 +1,19 @@
+[build]
+target = [
+    "riscv32imac-unknown-none-elf",
+    "thumbv6m-none-eabi",
+    "thumbv7em-none-eabihf",
+    "x86_64-unknown-linux-gnu",
+]
+
+[target.x86_64-unknown-linux-gnu]
+rustflags = [
+    "-C", "linker=rust-lld",
+    "-C", "linker-flavor=ld.lld",
+    "-C", "relocation-model=static",
+]
+
+[unstable]
+unstable-options = true
+build-std = ["core", "panic_abort"]
+build-std-features = ["compiler-builtins-mem"]
diff --git a/ctutils/checkct/Cargo.lock b/ctutils/checkct/Cargo.lock
new file mode 100644
index 00000000..fc3ab105
--- /dev/null
+++ b/ctutils/checkct/Cargo.lock
@@ -0,0 +1,87 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "checkct_macros"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "cmov"
+version = "0.5.4"
+
+[[package]]
+name = "ctutils"
+version = "0.4.3"
+dependencies = [
+ "cmov",
+]
+
+[[package]]
+name = "driver"
+version = "0.0.0"
+dependencies = [
+ "checkct_macros",
+ "ctutils",
+ "rand_core 0.10.1",
+ "rand_core 0.6.4",
+ "rand_core 0.9.5",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+
+[[package]]
+name = "rand_core"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76afc826de14238e6e8c374ddcc1fa19e374fd8dd986b0d2af0d02377261d83c"
+
+[[package]]
+name = "rand_core"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "63b8176103e19a2643978565ca18b50549f6101881c443590420e4dc998a3c69"
+
+[[package]]
+name = "syn"
+version = "2.0.119"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "872831b642d1a07999a962a351ed35b955ea2cfc8f3862091e2a240a84f17297"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2c754d6c33795a1c324727428e5a7dedb5b06195f9890bdbcba760d3e246563"
diff --git a/ctutils/checkct/Cargo.toml b/ctutils/checkct/Cargo.toml
new file mode 100644
index 00000000..d9436b8a
--- /dev/null
+++ b/ctutils/checkct/Cargo.toml
@@ -0,0 +1,12 @@
+cargo-features = ["panic-immediate-abort"]
+
+[workspace]
+members = ["driver"]
+resolver = "2"
+
+[profile.release]
+debug = true
+panic = "immediate-abort"
+
+[patch.crates-io]
+cmov = { path = "../../cmov" }
diff --git a/ctutils/checkct/checkct_macros/Cargo.toml b/ctutils/checkct/checkct_macros/Cargo.toml
new file mode 100644
index 00000000..559aaf47
--- /dev/null
+++ b/ctutils/checkct/checkct_macros/Cargo.toml
@@ -0,0 +1,14 @@
+#----- AUTOGENERATED BY CARGO-CHECKCT: DO NOT MODIFY -----
+[package]
+name = "checkct_macros"
+version = "0.1.0"
+publish = false
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0.86"
+quote = "1.0.37"
+syn = { version = "2.0.77", features = ["full"] }
diff --git a/ctutils/checkct/checkct_macros/src/lib.rs b/ctutils/checkct/checkct_macros/src/lib.rs
new file mode 100644
index 00000000..2051302e
--- /dev/null
+++ b/ctutils/checkct/checkct_macros/src/lib.rs
@@ -0,0 +1,91 @@
+use proc_macro::TokenStream;
+use proc_macro2::{Literal, Span};
+use quote::quote;
+use syn::{
+    parse::{Parse, ParseStream},
+    parse_macro_input, Error, Ident, ItemFn, LitStr, Result, Token,
+};
+
+struct AttributeArgs {
+    descriptor_link_section: Option<String>,
+}
+
+impl Parse for AttributeArgs {
+    fn parse(input: ParseStream) -> Result<Self> {
+        if input.is_empty() {
+            return Ok(Self {
+                descriptor_link_section: None,
+            });
+        }
+
+        let arg_name: Ident = input.parse()?;
+        if arg_name != "descriptor_link_section" {
+            return Err(Error::new(
+                arg_name.span(),
+                "expected `descriptor_link_section`",
+            ));
+        }
+        input.parse::<Token![=]>()?;
+        let descriptor_link_section: LitStr = input.parse()?;
+
+        Ok(Self {
+            descriptor_link_section: Some(descriptor_link_section.value()),
+        })
+    }
+}
+
+#[proc_macro_attribute]
+pub fn checkct(args: TokenStream, input: TokenStream) -> TokenStream {
+    let args = parse_macro_input!(args as AttributeArgs);
+    // By default the descriptor will be stored in the .note.checkct section
+    let descriptor_link_section = Literal::string(
+        args.descriptor_link_section
+            .as_deref()
+            .unwrap_or(".note.checkct"),
+    );
+
+    let item_fn = parse_macro_input!(input as ItemFn);
+    let name = &item_fn.sig.ident;
+
+    let entrypoint_descriptor_name = Ident::new(
+        &format!("__checkct_entrypoint_descriptor__{name}"),
+        Span::call_site(),
+    );
+    let entrypoint_descriptor_type = Ident::new(
+        &format!("__CheckctEntrypointDescriptor__{name}"),
+        Span::call_site(),
+    );
+
+    quote! {
+        // The descriptor is laid out as an ELF note (which binsec parses), since it is stored
+        // in a note section by default. It ends with the address of the entrypoint.
+        #[doc(hidden)]
+        #[allow(non_camel_case_types, dead_code)]
+        #[repr(C, packed(4))]
+        pub struct #entrypoint_descriptor_type {
+            namesz: u32,
+            descsz: u32,
+            kind: u32,
+            name: [u8; 8],
+            entrypoint: fn(),
+        }
+
+        // This variable is used to prevent the compiler from removing the code of the entrypoint
+        // function if it is unused. Moreover this variable name has a special format which allows
+        // cargo-checkct to find it.
+        // Make sure that the descriptor link section is kept by the linker.
+        #[unsafe(link_section = #descriptor_link_section)]
+        #[used]
+        pub static #entrypoint_descriptor_name: #entrypoint_descriptor_type =
+            #entrypoint_descriptor_type {
+                namesz: 8,
+                descsz: ::core::mem::size_of::<fn()>() as u32,
+                kind: 1,
+                name: *b"checkct\0",
+                entrypoint: #name,
+            };
+
+        #item_fn
+    }
+    .into()
+}
diff --git a/ctutils/checkct/driver/Cargo.toml b/ctutils/checkct/driver/Cargo.toml
new file mode 100644
index 00000000..7532ab03
--- /dev/null
+++ b/ctutils/checkct/driver/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "driver"
+version = "0.0.0"
+publish = false
+edition = "2024"
+
+[dependencies]
+checkct_macros = { path = "../checkct_macros" }
+ctutils = { path = "../.." }
+# RNG traits supplied by cargo-checkct's generated rng.rs.
+rand_core = "0.10"
+rand_core_09 = { package = "rand_core", version = "0.9" }
+rand_core_06 = { package = "rand_core", version = "0.6" }
diff --git a/ctutils/checkct/driver/src/driver.rs b/ctutils/checkct/driver/src/driver.rs
new file mode 100644
index 00000000..6a507fb9
--- /dev/null
+++ b/ctutils/checkct/driver/src/driver.rs
@@ -0,0 +1,74 @@
+use crate::rng::{PrivateRng, PublicRng};
+use checkct_macros::checkct;
+use core::hint::black_box;
+use ctutils::{Choice, CtSelect};
+
+macro_rules! private_integer {
+    ($ty:ty) => {{
+        let mut bytes = [0u8; size_of::<$ty>()];
+        PrivateRng.fill_bytes(&mut bytes);
+        <$ty>::from_le_bytes(bytes)
+    }};
+}
+
+macro_rules! scalar_checks {
+    ($module:ident, $ty:ty, $from_lsb:ident, $from_lt:ident, $select:ident) => {
+        mod $module {
+            use super::*;
+
+            fn inputs() -> ($ty, $ty, $ty) {
+                // Keep both RNG hooks linked: the BINSEC script uses both.
+                black_box(PublicRng.next_u32());
+                (
+                    private_integer!($ty),
+                    private_integer!($ty),
+                    private_integer!($ty),
+                )
+            }
+
+            #[checkct]
+            pub fn choice_select() {
+                let (a, b, condition) = inputs();
+                black_box(select(a, b, condition));
+            }
+
+            #[inline(never)]
+            fn select(a: $ty, b: $ty, condition: $ty) -> $ty {
+                Choice::$from_lsb(condition).$select(a, b)
+            }
+
+            /// A single shift-and-subtract division step, as used in crypto-bigint.
+            /// Keep the comparison and selection together to test their optimization.
+            #[checkct]
+            pub fn choice_select_after_lt() {
+                let (a, b, _) = inputs();
+                black_box(subtract_if_ge(a, b));
+            }
+
+            #[inline(never)]
+            fn subtract_if_ge(a: $ty, b: $ty) -> $ty {
+                let choice = Choice::$from_lt(a, b);
+                choice.$select(a.wrapping_sub(b), a)
+            }
+
+            /// Compare the const helper with the cmov-backed trait on the same expression.
+            #[checkct]
+            pub fn ct_select_after_lt() {
+                let (a, b, _) = inputs();
+                black_box(subtract_if_ge_with_ct_select(a, b));
+            }
+
+            #[inline(never)]
+            fn subtract_if_ge_with_ct_select(a: $ty, b: $ty) -> $ty {
+                let choice = Choice::$from_lt(a, b);
+                a.wrapping_sub(b).ct_select(&a, choice)
+            }
+        }
+    };
+}
+
+scalar_checks!(u8_ops, u8, from_u8_lsb, from_u8_lt, select_u8);
+scalar_checks!(u16_ops, u16, from_u16_lsb, from_u16_lt, select_u16);
+scalar_checks!(u32_ops, u32, from_u32_lsb, from_u32_lt, select_u32);
+scalar_checks!(u64_ops, u64, from_u64_lsb, from_u64_lt, select_u64);
+// TODO: scalar_checks!(u128_ops, u128, from_u128_lsb, from_u128_lt, select_u128);
diff --git a/ctutils/checkct/driver/src/main.rs b/ctutils/checkct/driver/src/main.rs
new file mode 100644
index 00000000..b1b07dd7
--- /dev/null
+++ b/ctutils/checkct/driver/src/main.rs
@@ -0,0 +1,24 @@
+//----- AUTOGENERATED BY CARGO-CHECKCT: DO NOT MODIFY -----
+//
+#![no_std]
+#![no_main]
+
+mod driver;
+mod rng;
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    panic!()
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    __checkct_panic()
+}
+
+/// The analysis of a path stops when it reaches this function.
+#[unsafe(no_mangle)]
+#[inline(never)]
+pub extern "C" fn __checkct_panic() -> ! {
+    loop {}
+}
diff --git a/ctutils/checkct/driver/src/rng.rs b/ctutils/checkct/driver/src/rng.rs
new file mode 100644
index 00000000..2af279c9
--- /dev/null
+++ b/ctutils/checkct/driver/src/rng.rs
@@ -0,0 +1,110 @@
+//----- AUTOGENERATED BY CARGO-CHECKCT: DO NOT MODIFY -----
+//
+//! `PrivateRng` produces secret values, and `PublicRng` produces public values.
+//! Both provide `next_u32`, `next_u64` and `fill_bytes` methods, and implement
+//! the traits of rand_core 0.10, 0.9 and 0.6.
+#![allow(dead_code)]
+
+#[unsafe(no_mangle)]
+#[inline(never)]
+pub fn __checkct_private_rand() -> u8 {
+    unsafe { core::ptr::read_volatile(0xcafe as *const u8) }
+}
+
+#[unsafe(no_mangle)]
+#[inline(never)]
+pub fn __checkct_public_rand() -> u8 {
+    unsafe { core::ptr::read_volatile(0xf00d as *const u8) }
+}
+
+#[allow(unused_imports)]
+pub use rand_core::{CryptoRng, Rng};
+// Drivers generated by older versions of cargo-checkct import `RngCore`
+#[allow(unused_imports)]
+pub use rand_core_06::RngCore;
+
+pub struct PrivateRng;
+pub struct PublicRng;
+
+macro_rules! impl_rng {
+    ($rng:ident, $rand:ident) => {
+        impl $rng {
+            pub const fn new() -> Self {
+                Self
+            }
+
+            pub fn next_u32(&mut self) -> u32 {
+                u32::from_be_bytes([$rand(), $rand(), $rand(), $rand()])
+            }
+
+            pub fn next_u64(&mut self) -> u64 {
+                (self.next_u32() as u64) << 32 | (self.next_u32() as u64)
+            }
+
+            pub fn fill_bytes(&mut self, dest: &mut [u8]) {
+                for d in dest {
+                    *d = $rand();
+                }
+            }
+        }
+
+        impl rand_core::TryRng for $rng {
+            type Error = core::convert::Infallible;
+
+            fn try_next_u32(&mut self) -> Result<u32, Self::Error> {
+                Ok($rng::next_u32(self))
+            }
+
+            fn try_next_u64(&mut self) -> Result<u64, Self::Error> {
+                Ok($rng::next_u64(self))
+            }
+
+            fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Self::Error> {
+                $rng::fill_bytes(self, dest);
+                Ok(())
+            }
+        }
+
+        impl rand_core::TryCryptoRng for $rng {}
+
+        impl rand_core_09::RngCore for $rng {
+            fn next_u32(&mut self) -> u32 {
+                $rng::next_u32(self)
+            }
+
+            fn next_u64(&mut self) -> u64 {
+                $rng::next_u64(self)
+            }
+
+            fn fill_bytes(&mut self, dest: &mut [u8]) {
+                $rng::fill_bytes(self, dest)
+            }
+        }
+
+        impl rand_core_09::CryptoRng for $rng {}
+
+        impl rand_core_06::RngCore for $rng {
+            fn next_u32(&mut self) -> u32 {
+                $rng::next_u32(self)
+            }
+
+            fn next_u64(&mut self) -> u64 {
+                $rng::next_u64(self)
+            }
+
+            fn fill_bytes(&mut self, dest: &mut [u8]) {
+                $rng::fill_bytes(self, dest)
+            }
+
+            fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core_06::Error> {
+                $rng::fill_bytes(self, dest);
+                Ok(())
+            }
+        }
+
+        impl rand_core_06::CryptoRng for $rng {}
+    };
+}
+
+impl_rng!(PrivateRng, __checkct_private_rand);
+impl_rng!(PublicRng, __checkct_public_rand);
diff --git a/ctutils/checkct/rust-toolchain.toml b/ctutils/checkct/rust-toolchain.toml
new file mode 100644
index 00000000..3e71075b
--- /dev/null
+++ b/ctutils/checkct/rust-toolchain.toml
@@ -0,0 +1,5 @@
+[toolchain]
+# Pinned so that driver builds are reproducible, since they rely on the unstable `-Zbuild-std`
+channel = "nightly-2026-10-06"
+profile = "minimal"
+components = ["rust-src"]
diff --git a/ctutils/src/choice.rs b/ctutils/src/choice.rs
index d6a8415b..b858e438 100644
--- a/ctutils/src/choice.rs
+++ b/ctutils/src/choice.rs
@@ -429,7 +429,7 @@ impl Choice {
     #[inline]
     #[must_use]
     pub const fn to_u8_mask(self) -> u8 {
-        self.0.wrapping_neg()
+        self.to_u8().wrapping_neg()
     }
 
     /// Create a `u16` bitmask.
@@ -440,7 +440,7 @@ impl Choice {
     #[inline]
     #[must_use]
     pub const fn to_u16_mask(self) -> u16 {
-        (self.0 as u16).wrapping_neg()
+        (self.to_u8() as u16).wrapping_neg()
     }
 
     /// Create a `u32` bitmask.
@@ -451,7 +451,7 @@ impl Choice {
     #[inline]
     #[must_use]
     pub const fn to_u32_mask(self) -> u32 {
-        (self.0 as u32).wrapping_neg()
+        (self.to_u8() as u32).wrapping_neg()
     }
 
     /// Create a `u64` bitmask.
@@ -462,7 +462,7 @@ impl Choice {
     #[inline]
     #[must_use]
     pub const fn to_u64_mask(self) -> u64 {
-        (self.0 as u64).wrapping_neg()
+        (self.to_u8() as u64).wrapping_neg()
     }
 
     /// Create a `u128` bitmask.
@@ -473,7 +473,7 @@ impl Choice {
     #[inline]
     #[must_use]
     pub const fn to_u128_mask(self) -> u128 {
-        (self.0 as u128).wrapping_neg()
+        (self.to_u8() as u128).wrapping_neg()
     }
 }