diff --git a/.eleventy.js b/.eleventy.js
index 4a41844..0c4fd68 100644
--- a/.eleventy.js
+++ b/.eleventy.js
@@ -1,4 +1,7 @@
 const { DateTime } = require("luxon");
+const metadata = require("./_data/metadata.json");
+const absoluteUrl = require("./_src/absoluteUrl");
+const HtmlToAbsoluteUrls = require("./_src/HtmlToAbsoluteUrls");
 const highlighters = require("./_src/eleventy-liquidjs-tag-highlight");
 
 function dateToISO(dateObj) {
@@ -24,6 +27,21 @@ module.exports = function(eleventyConfig) {
     return DateTime.fromJSDate(dateObj).toFormat("dd LLL yyyy");
   });
 
+  eleventyConfig.addNunjucksFilter("absoluteUrl", function(href, base) {
+    return absoluteUrl(href, base);
+  });
+
+  eleventyConfig.addNunjucksFilter("htmlToAbsoluteUrls", function(htmlContent, base, callback) {
+    if(!htmlContent) {
+      callback(null, "");
+      return;
+    }
+
+    HtmlToAbsoluteUrls(htmlContent, base, callback).then(result => {
+      callback(null, result.html);
+    });
+  }, true);
+
   // compatibility with existing {% highlight js %} and others
   eleventyConfig.addLiquidTag("highlight", highlighters.prismjs);
 
diff --git a/_src/AbsoluteUrl.js b/_src/AbsoluteUrl.js
new file mode 100644
index 0000000..f85fcc0
--- /dev/null
+++ b/_src/AbsoluteUrl.js
@@ -0,0 +1,5 @@
+const { URL } = require("url");
+
+module.exports = function(url, base) {
+	return (new URL(url, base)).toString()
+};
\ No newline at end of file
diff --git a/_src/HtmlToAbsoluteUrls.js b/_src/HtmlToAbsoluteUrls.js
new file mode 100644
index 0000000..d71717e
--- /dev/null
+++ b/_src/HtmlToAbsoluteUrls.js
@@ -0,0 +1,20 @@
+const posthtml = require('posthtml');
+const urls = require('posthtml-urls')
+const absoluteUrl = require("./AbsoluteUrl");
+
+module.exports = function(htmlContent, base) {
+  let options = {
+    eachURL: function(url, attr, element) {
+    	// #anchor in-page
+    	if( url.trim().indexOf("#") === 0 ) {
+    		return url;
+    	}
+
+    	return absoluteUrl(url, base);
+    }
+  };
+
+  let modifier = posthtml().use(urls(options));
+
+  return modifier.process(htmlContent);
+};
diff --git a/_src/test/HtmlToAbsoluteUrlsTest.js b/_src/test/HtmlToAbsoluteUrlsTest.js
new file mode 100644
index 0000000..e039e4e
--- /dev/null
+++ b/_src/test/HtmlToAbsoluteUrlsTest.js
@@ -0,0 +1,9 @@
+import test from "ava";
+import htmlToAbsUrls from "../HtmlToAbsoluteUrls.js";
+
+test("Changes a link href", async t => {
+  t.is((await htmlToAbsUrls(`<a href="#testanchor">Hello</a>`, "http://example.com/")).html, `<a href="#testanchor">Hello</a>`);
+  t.is((await htmlToAbsUrls(`<a href="/test.html">Hello</a>`, "http://example.com/")).html, `<a href="http://example.com/test.html">Hello</a>`);
+  t.is((await htmlToAbsUrls(`<img src="/test.png">`, "http://example.com/")).html, `<img src="http://example.com/test.png">`);
+  t.is((await htmlToAbsUrls(`<a href="http://someotherdomain/">Hello</a>`, "http://example.com/")).html, `<a href="http://someotherdomain/">Hello</a>`);
+});
diff --git a/feed/feed.njk b/feed/feed.njk
index 2754226..86ee46a 100644
--- a/feed/feed.njk
+++ b/feed/feed.njk
@@ -16,10 +16,10 @@ permalink: feed/feed.xml
 	{% for post in collections.posts %}
 	<entry>
 		<title>{{ post.data.title }}</title>
-		<link href="{{ metadata.url }}{{ post.url }}"/>
+		<link href="{{ post.url | absoluteUrl(metadata.url) }}"/>
 		<updated>{{ post.date | rssDate }}</updated>
-		<id>{{ metadata.url }}{{ post.url }}</id>
-		<content type="html">{{ post.templateContent }}</content>
+		<id>{{ post.url | absoluteUrl(metadata.url) }}</id>
+		<content type="html">{{ post.templateContent | htmlToAbsoluteUrls(metadata.url) }}</content>
 	</entry>
 	{% endfor %}
 </feed>
\ No newline at end of file
diff --git a/package.json b/package.json
index 5e1adec..b588033 100644
--- a/package.json
+++ b/package.json
@@ -21,9 +21,22 @@
     "url": "https://github.com/11ty/eleventy-base-blog/issues"
   },
   "homepage": "https://github.com/11ty/eleventy-base-blog#readme",
-  "devDependencies": {
-    "@11ty/eleventy": ">=0.2.11",
+  "dependencies": {
+    "@11ty/eleventy": "0.2.12",
     "luxon": "^0.3.1",
+    "posthtml": "^0.11.2",
+    "posthtml-urls": "^1.0.0",
     "prismjs": "^1.10.0"
+  },
+  "devDependencies": {
+    "ava": "^0.25.0"
+  },
+  "ava": {
+    "files": [
+      "_src/test/*.js"
+    ],
+    "source": [
+      "_src/**/*.{js,jsx}"
+    ]
   }
 }