diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 69fe819..45a6f90 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -45,6 +45,9 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest]
         channel: [stable, beta]
+        include:
+          - os: ubuntu-latest
+            channel: "1.62.0"
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
diff --git a/README.md b/README.md
index f2a9db0..3aba0bc 100644
--- a/README.md
+++ b/README.md
@@ -22,8 +22,15 @@ and are regularly updated.
 
 [nixpkgs]: https://github.com/NixOS/nixpkgs
 
+Note: This package requires a relatively new version of Rust to compile.
+You need at least `nixpkgs-unstable` to build it.
+
 - If you use `nix-env`, run `nix-env -iA nixpkgs.nil`
 - If you use `nix profile`, run `nix profile install nixpkgs#nil`
+- If you want to compile it from source.
+  1. Install stable Rust toolchain >= 1.62
+  1. Install `nix` >= 2.4 and make the binary `nix` available from your `PATH`.
+  1. Build and install via `cargo install --git https://github.com/oxalica/nil nil`
 
 ## Flake
 
diff --git a/crates/builtin/Cargo.toml b/crates/builtin/Cargo.toml
index fe2809c..8f175aa 100644
--- a/crates/builtin/Cargo.toml
+++ b/crates/builtin/Cargo.toml
@@ -3,6 +3,7 @@ name = "builtin"
 version = "0.0.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
+rust-version = "1.62"
 
 [dependencies]
 phf = "0.11.1"
diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
index 08323ba..0c1583e 100644
--- a/crates/ide/Cargo.toml
+++ b/crates/ide/Cargo.toml
@@ -3,6 +3,7 @@ name = "ide"
 version = "0.0.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
+rust-version = "1.62"
 
 [dependencies]
 builtin = { path = "../builtin" }
diff --git a/crates/nil/Cargo.toml b/crates/nil/Cargo.toml
index 76432e5..5cc6104 100644
--- a/crates/nil/Cargo.toml
+++ b/crates/nil/Cargo.toml
@@ -3,6 +3,7 @@ name = "nil"
 version = "0.0.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
+rust-version = "1.62"
 
 [dependencies]
 crossbeam-channel = "0.5.6"
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index a2b3ff3..32018cc 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -3,6 +3,7 @@ name = "syntax"
 version = "0.0.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
+rust-version = "1.62"
 
 [dependencies]
 once_cell = "1.13.0"