diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index ef3f30b1c..8845891e4 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -71,10 +71,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Install Rust (${{ vars.RUST_VERSION_EXTERNAL_TYPES }})
+      - name: Install Rust nightly
         uses: actions-rust-lang/setup-rust-toolchain@v1.10.1
         with:
-          toolchain: ${{ vars.RUST_VERSION_EXTERNAL_TYPES }}
+          toolchain: nightly-2024-10-18
 
       - name: Install just
         uses: taiki-e/install-action@v2.45.6
@@ -87,7 +87,7 @@ jobs:
           tool: cargo-check-external-types
 
       - name: check external types
-        run: just check-external-types-all +${{ vars.RUST_VERSION_EXTERNAL_TYPES }}
+        run: just check-external-types-all +nightly-2024-10-18
 
   public-api-diff:
     runs-on: ubuntu-latest
@@ -100,10 +100,10 @@ jobs:
       - name: Checkout PR branch
         uses: actions/checkout@v4
 
-      - name: Install Rust (${{ vars.RUST_VERSION_API_DIFF }})
+      - name: Install Rust nightly
         uses: actions-rust-lang/setup-rust-toolchain@v1.10.1
         with:
-          toolchain: ${{ vars.RUST_VERSION_API_DIFF }}
+          toolchain: nightly-2024-10-18
 
       - name: Install cargo-public-api
         uses: taiki-e/install-action@v2.45.6