diff --git a/.github/workflows/deploy_docs.yml b/.github/workflows/deploy_docs.yml
index fc48739028..83a992b4c8 100644
--- a/.github/workflows/deploy_docs.yml
+++ b/.github/workflows/deploy_docs.yml
@@ -27,7 +27,7 @@ jobs:
       - name: Install jq
         run: sudo apt-get install -y jq
 
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.66.0
       - run: cargo doc
 
       - name: Setup mdBook
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 756290eb8a..21b669b04e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,7 +37,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Install Rust toolchain
-      uses: dtolnay/rust-toolchain@1.65.0
+      uses: dtolnay/rust-toolchain@1.66.0
       with:
         targets: ${{ matrix.job.target }}
 
@@ -66,7 +66,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.66.0
       # This runs tests that rely on the MIME database being present.
       - run: cargo test -- --ignored
 
@@ -83,7 +83,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.66.0
       - name: Generate output for all sample files
         run: ./sample_files/compare_all.sh
       - name: Verify output is unchanged
@@ -94,7 +94,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.66.0
       - run: cargo package --allow-dirty
 
   fmt:
@@ -102,7 +102,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.65.0
+      - uses: dtolnay/rust-toolchain@1.66.0
       - run: cargo fmt --all -- --check
 
   actionlint:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cbb941f7d3..1731f3c3fe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,10 @@ version.**
 Fixed a crash (introduced in 0.60) when the final line in a file does
 not have a trailing newline and occurs more than once in the file.
 
+### Build
+
+difftastic now requires Rust 1.66 to build.
+
 ## 0.60 (released 1st August 2024)
 
 ### Diffing
diff --git a/Cargo.toml b/Cargo.toml
index e2f33d7179..23b41f9fb5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,16 +9,13 @@ authors = ["Wilfred Hughes <me@wilfred.me.uk>"]
 keywords = ["diff", "syntax"]
 categories = ["development-tools", "command-line-utilities", "parser-implementations"]
 edition = "2021"
-# Goal: support at least 12 months of Rust versions, and also the Rust
-# version on Debian stable (see https://tracker.debian.org/pkg/rustc,
-# currently 1.63).
+# Goal: support at least 12 months of Rust versions, and be
+# conservative about upgrades to help packagers.
 #
-# Unfortunately tree-sitter 0.20.10 has an MSRV[1] of 1.65, and it has
-# a bugfix[2] we want.
-#
-# 1: https://github.com/tree-sitter/tree-sitter/issues/2669
-# 2: https://github.com/Wilfred/difftastic/issues/570
-rust-version = "1.65.0"
+# For reference, Debian stable is on 1.63 (see
+# https://tracker.debian.org/pkg/rustc) but Debian doesn't currently
+# package difftastic. Other distros are somewhat newer.
+rust-version = "1.66.0"
 include = [
         "/build.rs",
         "/src/",
diff --git a/manual/src/from_source.md b/manual/src/from_source.md
index 5361ec427b..a7204b2e07 100644
--- a/manual/src/from_source.md
+++ b/manual/src/from_source.md
@@ -4,7 +4,7 @@
 
 Difftastic is written in Rust, so you will need Rust installed. I
 recommend [rustup](https://rustup.rs/) to install Rust. Difftastic
-requires Rust version 1.65 or later.
+requires Rust version 1.66 or later.
 
 You will also need a C++ compiler that supports C++14. If you're using
 GCC, you need at least version 8.
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 5daeec341b..b4d3b7acb9 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "1.65"
+channel = "1.66"
 components = ["rustfmt"]
 profile = "minimal"