diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f156ee3..bdce071 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,9 +18,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          components: clippy, rustfmt
+        run: rustup show
 
       - name: Install protoc
         # Issue #28: prost-build needs protoc to compile our internal
@@ -60,7 +58,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-toolchain@stable
+        run: rustup show
 
       - name: Install protoc
         # Issue #28: prost-build needs protoc; ubuntu-latest does not
diff --git a/DEVELOPER.md b/DEVELOPER.md
index 29b2322..bf254af 100644
--- a/DEVELOPER.md
+++ b/DEVELOPER.md
@@ -2,10 +2,12 @@
 
 ## Prerequisites
 
-- **Rust stable** (1.80+): install via [rustup](https://rustup.rs/)
+- **Rust**: install via [rustup](https://rustup.rs/)
   ```
   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   ```
+  The exact toolchain version is pinned in `rust-toolchain.toml` at the workspace root.
+  `rustup` reads this file automatically — no manual version selection needed.
 - **Git**
 
 ## Python bindings (`merutable-python`)
diff --git a/crates/merutable/Cargo.toml b/crates/merutable/Cargo.toml
index a9632ea..d59a1b1 100644
--- a/crates/merutable/Cargo.toml
+++ b/crates/merutable/Cargo.toml
@@ -4,6 +4,7 @@ version       = "0.0.1"
 edition       = "2021"
 description   = "Embeddable single-table engine: row + columnar Parquet with Iceberg-compatible metadata"
 keywords      = ["embedded", "lsm", "iceberg", "parquet", "table"]
+rust-version  = "1.88.0"
 license       = "Apache-2.0"
 repository    = "https://github.com/merutable/merutable"
 homepage      = "https://github.com/merutable/merutable"
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
new file mode 100644
index 0000000..d0ead5e
--- /dev/null
+++ b/rust-toolchain.toml
@@ -0,0 +1,3 @@
+[toolchain]
+channel = "stable"
+components = ["clippy", "rustfmt"]