diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 36395c8..2b20b51 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -14,7 +14,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - uses: dtolnay/rust-toolchain@stable
+    - uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # master
+      with:
+        toolchain: 1.85.0
     - uses: taiki-e/install-action@a37010ded18ff788be4440302bd6830b1ae50d8b # v2.68.25
       with:
         tool: cargo-hack@0.6.43
diff --git a/Cargo.toml b/Cargo.toml
index d2c6c6a..d7e0f3b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,7 +6,7 @@ license = "MIT OR Apache-2.0"
 description = "Types for rustdoc's json output"
 repository = "https://github.com/rust-lang/rustdoc-types"
 include = ["Cargo.toml", "CHANGELOG.md", "README.md", "LICENSE-MIT", "LICENSE-APACHE", "src/**/*.rs"]
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+rust-version = "1.85.0"
 
 [dependencies]
 serde = {version="1.0.186"}