diff --git a/editions/tw5.com/tiddlers/widgets/CodeblockWidget.tid b/editions/tw5.com/tiddlers/widgets/CodeblockWidget.tid
index 5592b3b45..acdab9ef9 100644
--- a/editions/tw5.com/tiddlers/widgets/CodeblockWidget.tid
+++ b/editions/tw5.com/tiddlers/widgets/CodeblockWidget.tid
@@ -1,6 +1,6 @@
 caption: codeblock
 created: 20151103160200000
-modified: 20151103160200000
+modified: 20160817175325205
 tags: Widgets
 title: CodeBlockWidget
 type: text/vnd.tiddlywiki
@@ -16,9 +16,14 @@ displayed monospace. A language may optionally be specified using the
 
 The content of the `<$codeblock>` widget is ignored.
 
-|!Attribute |!Description|
-|code|Contents of the block to render as code|
-|language|Programming language for syntax highlighting|
+|!Attribute |!Description |
+|code |Contents of the block to render as code |
+|language |Programming language for syntax highlighting |
+
+The `language` attribute accepts either:
+
+* a Highlight.js language code (see https://highlightjs.org/static/demo/ for a list)
+* a MIME type (eg, `text/html` or `image/svg+xml`)
 
 ! Examples
 
diff --git a/plugins/tiddlywiki/highlight/TypeMappings.multids b/plugins/tiddlywiki/highlight/TypeMappings.multids
new file mode 100644
index 000000000..0bf0ef87e
--- /dev/null
+++ b/plugins/tiddlywiki/highlight/TypeMappings.multids
@@ -0,0 +1,9 @@
+title: $:/config/HighlightPlugin/TypeMappings/
+
+text/plain:
+application/javascript: javascript
+application/json: json
+text/css: css
+text/html: html
+image/svg+xml: xml
+text/x-markdown: markdown
diff --git a/plugins/tiddlywiki/highlight/highlightblock.js b/plugins/tiddlywiki/highlight/highlightblock.js
index a2187e8d7..70f8d5899 100644
--- a/plugins/tiddlywiki/highlight/highlightblock.js
+++ b/plugins/tiddlywiki/highlight/highlightblock.js
@@ -12,6 +12,8 @@ Wraps up the fenced code blocks parser for highlight and use in TiddlyWiki5
 /*global $tw: false */
 "use strict";
 
+var TYPE_MAPPINGS_BASE = "$:/config/HighlightPlugin/TypeMappings/";
+
 var CodeBlockWidget = require("$:/core/modules/widgets/codeblock.js").codeblock;
 
 var hljs = require("$:/plugins/tiddlywiki/highlight/highlight.js");
@@ -19,14 +21,19 @@ var hljs = require("$:/plugins/tiddlywiki/highlight/highlight.js");
 hljs.configure({tabReplace: "    "});	
 
 CodeBlockWidget.prototype.postRender = function() {
-	var domNode = this.domNodes[0];
-	if($tw.browser && this.document !== $tw.fakeDocument && this.language) {
-		domNode.className = this.language.toLowerCase();
+	var domNode = this.domNodes[0],
+		language = this.language,
+		tiddler = this.wiki.getTiddler(TYPE_MAPPINGS_BASE + language);
+	if(tiddler && tiddler.fields.text) {
+		language = tiddler.fields.text;
+	}
+	if($tw.browser && this.document !== $tw.fakeDocument && language) {
+		domNode.className = language.toLowerCase();
 		hljs.highlightBlock(domNode);
-	} else if(!$tw.browser && this.language && this.language.indexOf("/") === -1 ){
+	} else if(!$tw.browser && language && language.indexOf("/") === -1 ){
 		try {
-			domNode.className = this.language.toLowerCase() + " hljs";
-			domNode.children[0].innerHTML = hljs.fixMarkup(hljs.highlight(this.language, this.getAttribute("code")).value);
+			domNode.className = language.toLowerCase() + " hljs";
+			domNode.children[0].innerHTML = hljs.fixMarkup(hljs.highlight(language, this.getAttribute("code")).value);
 		}
 		catch(err) {
 			// Can't easily tell if a language is registered or not in the packed version of hightlight.js,
diff --git a/plugins/tiddlywiki/highlight/readme.tid b/plugins/tiddlywiki/highlight/readme.tid
index 2b645432a..59001fc85 100644
--- a/plugins/tiddlywiki/highlight/readme.tid
+++ b/plugins/tiddlywiki/highlight/readme.tid
@@ -45,3 +45,4 @@ The plugin includes support for the following languages (referred to as "brushes
 * sql
 * xml
 
+You can also specify the language as a MIME content type (eg `text/html` or `text/css`). The mapping is accomplished via mapping tiddlers whose titles start with `$:/config/HighlightPlugin/TypeMappings/`.