diff --git a/.prettierignore b/.prettierignore
index c3972d46..24cc5695 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -13,6 +13,7 @@ LICENSE
 /locale/
 /node_modules/
 /tests/fixtures/
+/coverage/
 
 # white-list files we want to process
 !*.js
diff --git a/.prettierrc b/.prettierrc
index f923252f..d6b27744 100644
--- a/.prettierrc
+++ b/.prettierrc
@@ -15,6 +15,12 @@
       "options": {
         "parser": "babel"
       }
+    },
+    {
+      "files": "*.md",
+      "options": {
+        "proseWrap": "preserve"
+      }
     }
   ]
 }
diff --git a/.travis.yml b/.travis.yml
index 73b43918..5475d34b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,7 @@ script:
   - npm run lint
   # run integration tests using an addons-linter binary in a production-like environment
   - npm run test-integration:production
+  - npm run prettier-ci
 notifications:
   slack:
     if: branch = master
diff --git a/README.md b/README.md
index c03eb397..2177f6fe 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,7 @@ Dependencies are automatically kept up-to-date using [renovatebot](https://renov
 | npm run test-coverage-once      | Runs the tests once with coverage                                                |
 | npm run test-integration-linter | Runs our integration test-suite                                                  |
 | npm run prettier                | Automatically format the whole code-base with Prettier                           |
+| npm run prettier-ci             | Run [Prettier][] and fail if some code has been changed without being formatted  |
 | npm run prettier-dev            | Automatically compare and format modified source files against the master branch |
 
 ### Building
@@ -221,3 +222,4 @@ After merging the PR, [create a new release][new release] with the same tag name
 
 [new release]: https://github.com/mozilla/addons-linter/releases/new
 [semver]: http://semver.org/
+[prettier]: https://prettier.io/
diff --git a/docs/rules.md b/docs/rules.md
index c4cb7ca5..ffdd5ec5 100644
--- a/docs/rules.md
+++ b/docs/rules.md
@@ -6,26 +6,26 @@ Rules are sorted by severity.
 
 ## JavaScript
 
-| Message code               | Severity | Description                                                                            |
-| -------------------------- | -------- | -------------------------------------------------------------------------------------- |
-| `KNOWN_LIBRARY`            | notice   | This is version of a JS library is known and generally accepted.                       |
-| `OPENDIALOG_NONLIT_URI`    | notice   | openDialog called with non-literal parameter.                                          |
-| `EVENT_LISTENER_FOURTH`    | notice   | `addEventListener` called with truthy fourth argument.                                 |
-| `UNEXPECTED_GLOGAL_ARG`    | warning  | Unexpected global passed as an argument.                                               |
-| `NO_IMPLIED_EVAL`          | warning  | disallow the use of `eval()`-like methods.                                             |
-| `OPENDIALOG_REMOTE_URI`    | warning  | openDialog called with non-local URI.                                                  |
-| `NO_DOCUMENT_WRITE`        | warning  | Use of `document.write` strongly discouraged.                                          |
-| `JS_SYNTAX_ERROR`          | warning  | JavaScript compile-time error.                                                         |
-| `UNADVISED_LIBRARY`        | warning  | This version of a JS library is not recommended.                                       |
-| `DEPRECATED_API`           | warning  | API is deprecated.                                                                     |
-| `STORAGE_SYNC`             | warning  | Temporary IDs can cause issues with `storage.sync`.                                    |
-| `STORAGE_MANAGED`          | warning  | Temporary IDs can cause issues with `storage.managed`.                                 |
-| `IDENTITY_GETREDIRECTURL`  | warning  | Temporary IDs can cause issues with `identity.getRedirectURL`.                         |
-| `RUNTIME_ONMESSAGEEXTERNAL`| warning  | Temporary IDs can cause issues with `runtime.onMessageExternal`.                       |
-| `RUNTIME_ONCONNECTEXTERNAL`| warning  | Temporary IDs can cause issues with `runtime.onConnectExternal`.                       |
-| `BANNED_LIBRARY`           | error    | This version of a JS library is banned for security reasons.                           |
-| `INCOMPATIBLE_API`         | warning  | API not compatible with `applications.gecko.strict_min_version`                        |
-| `ANDROID_INCOMPATIBLE_API` | warning  | API not compatible with Firefox for Android at `applications.gecko.strict_min_version` |
+| Message code                | Severity | Description                                                                            |
+| --------------------------- | -------- | -------------------------------------------------------------------------------------- |
+| `KNOWN_LIBRARY`             | notice   | This is version of a JS library is known and generally accepted.                       |
+| `OPENDIALOG_NONLIT_URI`     | notice   | openDialog called with non-literal parameter.                                          |
+| `EVENT_LISTENER_FOURTH`     | notice   | `addEventListener` called with truthy fourth argument.                                 |
+| `UNEXPECTED_GLOGAL_ARG`     | warning  | Unexpected global passed as an argument.                                               |
+| `NO_IMPLIED_EVAL`           | warning  | disallow the use of `eval()`-like methods.                                             |
+| `OPENDIALOG_REMOTE_URI`     | warning  | openDialog called with non-local URI.                                                  |
+| `NO_DOCUMENT_WRITE`         | warning  | Use of `document.write` strongly discouraged.                                          |
+| `JS_SYNTAX_ERROR`           | warning  | JavaScript compile-time error.                                                         |
+| `UNADVISED_LIBRARY`         | warning  | This version of a JS library is not recommended.                                       |
+| `DEPRECATED_API`            | warning  | API is deprecated.                                                                     |
+| `STORAGE_SYNC`              | warning  | Temporary IDs can cause issues with `storage.sync`.                                    |
+| `STORAGE_MANAGED`           | warning  | Temporary IDs can cause issues with `storage.managed`.                                 |
+| `IDENTITY_GETREDIRECTURL`   | warning  | Temporary IDs can cause issues with `identity.getRedirectURL`.                         |
+| `RUNTIME_ONMESSAGEEXTERNAL` | warning  | Temporary IDs can cause issues with `runtime.onMessageExternal`.                       |
+| `RUNTIME_ONCONNECTEXTERNAL` | warning  | Temporary IDs can cause issues with `runtime.onConnectExternal`.                       |
+| `BANNED_LIBRARY`            | error    | This version of a JS library is banned for security reasons.                           |
+| `INCOMPATIBLE_API`          | warning  | API not compatible with `applications.gecko.strict_min_version`                        |
+| `ANDROID_INCOMPATIBLE_API`  | warning  | API not compatible with Firefox for Android at `applications.gecko.strict_min_version` |
 
 ## Markup
 
diff --git a/package.json b/package.json
index b9ec0849..5ea3cc8b 100644
--- a/package.json
+++ b/package.json
@@ -23,6 +23,7 @@
     "test-integration:production": "node tests/integration/run-as-production-env.js test-integration tests/integration/addons-linter",
     "lint": "npm run eslint",
     "prettier": "prettier --write '**'",
+    "prettier-ci": "prettier --list-different '**' || (echo '\n\nThis failure means you did not run `npm run prettier-dev` before committing\n\n' && exit 1)",
     "prettier-dev": "pretty-quick --branch master",
     "publish-rules": "scripts/build-rules && cp node_modules/gfm.css/gfm.css docs/html/gfm.css && scripts/publish-rules",
     "gen-contributing-toc": "doctoc CONTRIBUTING.md"