diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0722e6d8..13a89f19 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -180,7 +180,6 @@ jobs:
       - name: cargo test (${{ matrix.features }})
         run: cargo test --locked ${{ matrix.features }} -- --include-ignored
         env:
-          RUSTFLAGS: "-D warnings"
           AWS_LC_SYS_PREBUILT_NASM: "1" # for benefit of rcgen
 
   msrv:
@@ -238,7 +237,7 @@ jobs:
       - name: Install rust toolchain
         uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: nightly-2025-08-06
+          toolchain: nightly-2025-10-18
           # ^ sync with https://github.com/awslabs/cargo-check-external-types/blob/main/rust-toolchain.toml
       - name: Install cargo-check-external-types
         uses: taiki-e/cache-cargo-install-action@v2