diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 28e66960b..34482da42 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -17,11 +17,11 @@ jobs:
     - uses: actions/checkout@28c7f3d2b5162b5ddd3dfd9a45aa55eaf396478b
     - uses: actions-rs/toolchain@b223206e28798aa3c3668bdd6409258e6dc29172
       with:
-        toolchain: nightly-2020-06-02
+        toolchain: nightly-2020-07-26
         default: false
         components: rustfmt
     - name: Check style
-      run: cargo +nightly-2020-06-02 fmt -- --check
+      run: cargo +nightly-2020-07-26 fmt -- --check
 
   build-and-test:
     runs-on: ${{ matrix.os }}
diff --git a/.vscode/settings.json b/.vscode/settings.json
index fdfa83174..aa647e78a 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -2,7 +2,7 @@
     "rust-analyzer.rustfmt.overrideCommand": [
         "rustup",
         "run",
-        "nightly-2020-06-02",
+        "nightly-2020-07-26",
         "rustfmt"
     ]
 }
diff --git a/README.adoc b/README.adoc
index d9f291cdb..aa8aa0868 100644
--- a/README.adoc
+++ b/README.adoc
@@ -16,13 +16,28 @@ $ cargo +nightly doc
 ----
 
 
-== Build and run
+== Contributing
+
+=== Building and testing
 
 You can **build and run the whole test suite** with `cargo test`.  The test
 suite runs cleanly and should remain clean.
 
-You can **format the code** using `cargo +nightly fmt`.  Make sure to run this
-before pushing changes.  The CI checks that the code is correctly formatted.
+=== Code formatting
+
+Dropshot works with stable Rust versions, but for consistency the code is
+_formatted_ with a specific version of `rustfmt`.  To contribute to Dropshot,
+you will need to have installed the `nightly-2020-07-26` version of the Rust
+toolchain:
+
+----
+$ rustup install nightly-2020-07-26
+----
+
+You can then **format the code** using `cargo +nightly-2020-07-26 fmt` or
+`rustfmt +nightly-2020-07-26`.  Make sure to run this before pushing changes.
+The CI uses this version of `rustfmt` to check that the code is correctly
+formatted.
 
 
 == Configuration reference
diff --git a/rustfmt.toml b/rustfmt.toml
index 852e30fef..391cb7aac 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -83,7 +83,7 @@ use_field_init_shorthand = false
 force_explicit_abi = true
 condense_wildcard_suffixes = false
 color = "Auto"
-required_version = "1.4.15"
+required_version = "1.4.19"
 disable_all_formatting = false
 skip_children = false
 hide_parse_errors = false