diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2e6a6c3ae..378dd22aa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -42,14 +42,36 @@ jobs:
       matrix:
         target:
           - wasm32-wasi
-
+          - thumbv7em-none-eabihf
     steps:
       - uses: actions/checkout@v4
+        with:
+          path: crate_root
+      # We use a synthetic crate to ensure no dev-dependencies are enabled, which can
+      # be incompatible with some of these targets.
+      - name: Create synthetic crate for testing
+        run: cargo init --lib ci-build
+      - name: Copy Rust version into synthetic crate
+        run: cp crate_root/rust-toolchain.toml ci-build/
+      - name: Copy patch directives into synthetic crate
+        run: |
+          echo "[patch.crates-io]" >> ./ci-build/Cargo.toml
+          cat ./crate_root/Cargo.toml | sed "0,/.\+\(patch.crates.\+\)/d" >> ./ci-build/Cargo.toml
+      - name: Add no_std pragma to lib.rs
+        run: |
+          echo "#![no_std]" > ./ci-build/src/lib.rs
+      - name: Add sapling-crypto as a dependency of the synthetic crate
+        working-directory: ./ci-build
+        run: cargo add --no-default-features --path ../crate_root
+      - name: Add lazy_static with the spin_no_std feature
+        working-directory: ./ci-build
+        run: cargo add lazy_static --features "spin_no_std"
       - name: Add target
+        working-directory: ./ci-build
         run: rustup target add ${{ matrix.target }}
-      - run: cargo fetch
-      - name: Build for ${{ matrix.target }} target
-        run: cargo build --verbose --no-default-features --target ${{ matrix.target }}
+      - name: Build for target
+        working-directory: ./ci-build
+        run: cargo build --verbose --target ${{ matrix.target }}
 
   bitrot:
     name: Bitrot check
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 36e4da4b1..fc440977b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to Rust's notion of
 - `orchard::pczt::Zip32Derivation::extract_account_index`
 
 ### Changed
+- MSRV is now 1.66
 - Migrated to `nonempty 0.11`.
 
 ## [0.10.1] - 2024-12-16
diff --git a/Cargo.toml b/Cargo.toml
index 3194a57e7..24b3388e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,7 @@ authors = [
     "Kris Nuttycombe <kris@electriccoin.co>",
 ]
 edition = "2021"
-rust-version = "1.65"
+rust-version = "1.66"
 description = "The Orchard shielded transaction protocol"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/zcash/orchard"
diff --git a/README.md b/README.md
index c2138a11f..2bf2f424e 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,19 @@
 # orchard [![Crates.io](https://img.shields.io/crates/v/orchard.svg)](https://crates.io/crates/orchard) #
 
-Requires Rust 1.65+.
+Requires Rust 1.66+.
 
 ## Documentation
 
 - [The Orchard Book](https://zcash.github.io/orchard/)
 - [Crate documentation](https://docs.rs/orchard)
 
+## `no_std` compatibility
+
+Downstream users of this crate must enable the `spin_no_std` feature of the
+`lazy_static` crate in order to take advantage of `no_std` builds; this is due
+to the fact that `--no-default-features` builds of `lazy_static` still rely on
+`std`.
+
 ## License
 
 Copyright 2020-2023 The Electric Coin Company.
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 5ecda6e49..fb11b593c 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "1.65.0"
+channel = "1.66.0"
 components = [ "clippy", "rustfmt" ]