diff --git a/.github/workflows/external-types.yml b/.github/workflows/external-types.yml
index 2a74a396..e18b0e15 100644
--- a/.github/workflows/external-types.yml
+++ b/.github/workflows/external-types.yml
@@ -13,7 +13,7 @@ jobs:
       - name: Install toolchain
         uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: nightly
+          toolchain: nightly-2023-10-10
 
       - name: Install cargo-check-external-types
         run: cargo install --locked cargo-check-external-types