diff --git a/build-system/tasks/extension-generator/extension-doc.template.md b/build-system/tasks/extension-generator/extension-doc.template.md
new file mode 100644
index 000000000000..b0ab895f6b20
--- /dev/null
+++ b/build-system/tasks/extension-generator/extension-doc.template.md
@@ -0,0 +1,79 @@
+<!--
+  1. Change "category" below to one of:
+       ads-analytics
+       dynamic-content
+       layout
+       media
+       presentation
+       social
+  2. Remove any of the "formats" that don't apply.
+     You can also add the "ads" and "stories" formats if they apply.
+  3. And remove this comment! (no empty lines before "---")
+-->
+---
+$category: presentation
+formats:
+  - websites
+  - email
+teaser:
+  text: FILL THIS IN.
+---
+<!--
+Copyright ${year} The AMP HTML Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS-IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+# \`${name}\`
+
+<table>
+  <tr>
+    <td width="40%"><strong>Description</strong></td>
+    <td>FILL THIS IN</td>
+  </tr>
+  <tr>
+    <td width="40%"><strong>Availability</strong></td>
+    <td>FILL THIS IN</td>
+  </tr>
+  <tr>
+    <td width="40%"><strong>Required Script</strong></td>
+    <td><code>&lt;script async custom-element="${name}" src="https://cdn.ampproject.org/v0/${name}-0.1.js">&lt;/script></code></td>
+  </tr>
+  <tr>
+    <td class="col-fourty"><strong><a href="https://amp.dev/documentation/guides-and-tutorials/develop/style_and_layout/control_layout">Supported Layouts</a></strong></td>
+    <td>FILL THIS IN</td>
+  </tr>
+  <tr>
+    <td width="40%"><strong>Examples</strong></td>
+    <td>FILL THIS IN</td>
+  </tr>
+</table>
+
+## Behavior
+
+FILL THIS IN. What does this extension do?
+
+## Attributes
+
+FILL THIS IN. Does this extension allow for properties to configure?
+
+<table>
+  <tr>
+    <td width="40%"><strong>data-my-attribute</strong></td>
+    <td>FILL THIS IN. This table <strong>must</strong> be written in HTML.</td>
+  </tr>
+</table>
+
+## Validation
+
+See [${name} rules](https://github.com/ampproject/amphtml/blob/master/extensions/${name}/validator-${name}.protoascii) in the AMP validator specification.
diff --git a/build-system/tasks/extension-generator/index.js b/build-system/tasks/extension-generator/index.js
index abacd6a81b0a..eff0492b4b37 100644
--- a/build-system/tasks/extension-generator/index.js
+++ b/build-system/tasks/extension-generator/index.js
@@ -73,89 +73,11 @@ tags: {  # <${name}>
 `;
 }
 
-function getMarkdownExtensionFile(name) {
-  return `<!--
-  1. Change "category" below to one of:
-       ads-analytics
-       dynamic-content
-       layout
-       media
-       presentation
-       social
-
-  2. Remove any of the "formats" that don't apply.
-     You can also add the "ads" and "stories" formats if they apply.
-
-  3. And remove this comment! (no empty lines before "---")
--->
----
-$category: presentation
-formats:
-  - websites
-  - email
-teaser:
-  text: FILL THIS IN.
----
-<!--
-Copyright ${year} The AMP HTML Authors. All Rights Reserved.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-      http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS-IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
--->
-
-# \`${name}\`
-
-<table>
-  <tr>
-    <td width="40%"><strong>Description</strong></td>
-    <td>FILL THIS IN</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>Availability</strong></td>
-    <td>FILL THIS IN</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>Required Script</strong></td>
-    <td><code>&lt;script async custom-element="${name}" src="https://cdn.ampproject.org/v0/${name}-0.1.js">&lt;/script></code></td>
-  </tr>
-  <tr>
-    <td class="col-fourty"><strong><a href="https://amp.dev/documentation/guides-and-tutorials/develop/style_and_layout/control_layout">Supported Layouts</a></strong></td>
-    <td>FILL THIS IN</td>
-  </tr>
-  <tr>
-    <td width="40%"><strong>Examples</strong></td>
-    <td>FILL THIS IN</td>
-  </tr>
-</table>
-
-## Behavior
-
-FILL THIS IN. What does this extension do?
-
-## Attributes
-
-FILL THIS IN. Does this extension allow for properties to configure?
-
-<table>
-  <tr>
-    <td width="40%"><strong>data-my-attribute</strong></td>
-    <td>FILL THIS IN. This table <strong>must</strong> be written in HTML.</td>
-  </tr>
-</table>
-
-## Validation
-See [${name} rules](https://github.com/ampproject/amphtml/blob/master/extensions/${name}/validator-${name}.protoascii) in the AMP validator specification.
-`;
-}
+const getMarkdownDocFile = async name =>
+  (await fs.readFile(`${__dirname}/extension-doc.template.md`))
+    .toString('utf-8')
+    .replace(/\${name}/g, name)
+    .replace(/\${year}/g, year);
 
 function getJsTestExtensionFile(name) {
   return `/**
@@ -286,7 +208,7 @@ async function makeExtension() {
   fs.mkdirpSync(`extensions/${name}/0.1/test`);
   fs.writeFileSync(
     `extensions/${name}/${name}.md`,
-    getMarkdownExtensionFile(name)
+    await getMarkdownDocFile(name)
   );
   fs.writeFileSync(
     `extensions/${name}/validator-${name}.protoascii`,