diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0bd09e2..48aa1f3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,6 +11,12 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+# Fail every cargo invocation on warnings from workspace-local packages
+# (cargo's build.warnings, stable since 1.97). CI-only: local builds
+# still just warn.
+env:
+  CARGO_BUILD_WARNINGS: deny
+
 jobs:
   lean-test:
     name: Lean Tests
@@ -28,6 +34,11 @@ jobs:
     steps:
       - uses: actions/checkout@v7
       - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          # Warnings are handled by CARGO_BUILD_WARNINGS above, which applies
+          # to local packages only. The action defaults to `-D warnings`,
+          # which also denies warnings from dependencies.
+          rustflags: ""
       # Only restore the cache, since the `test` job will save the test binary to the cache first
       - uses: actions/cache/restore@v6
         with:
diff --git a/flake.nix b/flake.nix
index 67f3a2c..ed1c59f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -90,7 +90,7 @@
           # Pins the Rust toolchain
           rustToolchain = fenix.packages.${system}.fromToolchainFile {
             file = ./rust-toolchain.toml;
-            sha256 = "sha256-sqSWJDUxc+zaz1nBWMAJKTAGBuGWP25GCftIOlCEAtA=";
+            sha256 = "sha256-P30Tm3O7vQAE725YtDCDHGjNrSsfZO4us11UwJGZSJo=";
           };
 
           # Rust package
@@ -164,12 +164,14 @@
           };
 
           checks = {
-            # Lint the Rust FFI crate; warnings are errors.
+            # Lint the Rust FFI crate; the lint set lives in rust/Cargo.toml and
+            # CARGO_BUILD_WARNINGS promotes local-package warnings to errors.
             clippy = craneLib.cargoClippy (
               craneArgs
               // {
                 inherit cargoArtifacts;
-                cargoClippyExtraArgs = "--all-targets -- -D warnings";
+                CARGO_BUILD_WARNINGS = "deny";
+                cargoClippyExtraArgs = "--all-targets";
               }
             );
             # Run the Lean test suite (exercises both the C and Rust backends)
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index a5b578d..23de054 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
 # The default profile includes rustc, rust-std, cargo, rust-docs, rustfmt and clippy.
 profile = "default"
-channel = "1.92"
+channel = "1.98"
diff --git a/rust/Cargo.lock b/rust/Cargo.lock
index 3af6403..f22a78d 100644
--- a/rust/Cargo.lock
+++ b/rust/Cargo.lock
@@ -26,7 +26,7 @@ checksum = "f2032f911046de80f0a198e0901378627c33f59ea0ac00e363d481118bd70a53"
 [[package]]
 name = "bignat"
 version = "0.1.0"
-source = "git+https://github.com/argumentcomputer/lean-ffi?rev=2a9c91eba44ea791978a086a6a19b3a922edfee5#2a9c91eba44ea791978a086a6a19b3a922edfee5"
+source = "git+https://github.com/argumentcomputer/lean-ffi?rev=93c7e52952ae94546be08313f4ff3922984c84d5#93c7e52952ae94546be08313f4ff3922984c84d5"
 dependencies = [
  "num-bigint",
 ]
@@ -159,7 +159,7 @@ dependencies = [
 [[package]]
 name = "lean-ffi"
 version = "0.1.0"
-source = "git+https://github.com/argumentcomputer/lean-ffi?rev=2a9c91eba44ea791978a086a6a19b3a922edfee5#2a9c91eba44ea791978a086a6a19b3a922edfee5"
+source = "git+https://github.com/argumentcomputer/lean-ffi?rev=93c7e52952ae94546be08313f4ff3922984c84d5#93c7e52952ae94546be08313f4ff3922984c84d5"
 dependencies = [
  "bignat",
  "bindgen",
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 777f0a4..3606212 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -16,10 +16,64 @@ crate-type = ["staticlib", "cdylib"]
 
 [dependencies]
 blake3 = "1.8.7"
-lean-ffi = { git = "https://github.com/argumentcomputer/lean-ffi", rev = "2a9c91eba44ea791978a086a6a19b3a922edfee5" }
+lean-ffi = { git = "https://github.com/argumentcomputer/lean-ffi", rev = "93c7e52952ae94546be08313f4ff3922984c84d5" }
 
 [profile.dev]
 panic = "abort"
 
 [profile.release]
 panic = "abort"
+
+[lints.rust]
+invalid_reference_casting = "warn"
+nonstandard_style = { level = "warn", priority = -1 }
+rust_2018_idioms = { level = "warn", priority = -1 }
+trivial_numeric_casts = "warn"
+unreachable_pub = "warn"
+unused_lifetimes = "warn"
+unused_qualifications = "warn"
+
+[lints.clippy]
+all = { level = "warn", priority = -1 }
+# Casts
+cast_possible_truncation = "warn"
+cast_possible_wrap = "warn"
+cast_precision_loss = "warn"
+cast_sign_loss = "warn"
+char_lit_as_u8 = "warn"
+checked_conversions = "warn"
+fn_to_numeric_cast = "warn"
+fn_to_numeric_cast_with_truncation = "warn"
+invalid_upcast_comparisons = "warn"
+ptr_as_ptr = "warn"
+unnecessary_cast = "warn"
+# Everything else
+dbg_macro = "warn"
+derive_partial_eq_without_eq = "warn"
+disallowed_methods = "warn"
+enum_glob_use = "warn"
+explicit_into_iter_loop = "warn"
+fallible_impl_from = "warn"
+filter_map_next = "warn"
+flat_map_option = "warn"
+implicit_clone = "warn"
+inefficient_to_string = "warn"
+large_stack_arrays = "warn"
+large_types_passed_by_value = "warn"
+macro_use_imports = "warn"
+manual_assert = "warn"
+manual_ok_or = "warn"
+map_err_ignore = "warn"
+map_flatten = "warn"
+map_unwrap_or = "warn"
+match_same_arms = "warn"
+match_wild_err_arm = "warn"
+needless_borrow = "warn"
+needless_continue = "warn"
+needless_for_each = "warn"
+needless_pass_by_value = "warn"
+option_option = "warn"
+same_functions_in_if_condition = "warn"
+trait_duplication_in_bounds = "warn"
+unnecessary_wraps = "warn"
+unnested_or_patterns = "warn"