diff --git a/editions/test/tiddlers/tests/test-filters.js b/editions/test/tiddlers/tests/test-filters.js
index a79a242c8..628b41851 100644
--- a/editions/test/tiddlers/tests/test-filters.js
+++ b/editions/test/tiddlers/tests/test-filters.js
@@ -1062,7 +1062,7 @@ describe("Filter tests", function() {
 		});
 	
 		it("should handle the deserializers operator", function() {
-			var expectedDeserializers = ["application/javascript","application/json","application/x-tiddler","application/x-tiddler-html-div","application/x-tiddlers","text/css","text/html","text/plain","text/x-markdown"];
+			var expectedDeserializers = ["application/javascript","application/json","application/x-tiddler","application/x-tiddler-html-div","application/x-tiddlers","text/css","text/html","text/markdown","text/plain","text/x-markdown"];
 			if($tw.browser) {
 				expectedDeserializers.unshift("(DOM)");
 			}
diff --git a/plugins/tiddlywiki/markdown/frontmatter-deserializer.js b/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
index 38bd31089..39dc3bbee 100644
--- a/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
+++ b/plugins/tiddlywiki/markdown/frontmatter-deserializer.js
@@ -16,7 +16,7 @@ representation.
 
 var yaml = require("$:/plugins/tiddlywiki/markdown/yaml.js");
 
-exports["text/x-markdown"] = function(text,fields) {
+function deserialize(text,fields) {
 	var result = Object.create(null),
 		body = text,
 		frontmatter = null;
@@ -76,7 +76,12 @@ exports["text/x-markdown"] = function(text,fields) {
 		result.type = "text/x-markdown";
 	}
 	return [result];
-};
+}
+
+// Register under both types — text/x-markdown is the deserializer type
+// registered for .md file extensions; text/markdown is the raw content type.
+exports["text/x-markdown"] = deserialize;
+exports["text/markdown"] = deserialize;
 
 /*
 Convert a parsed YAML value to a tiddler field string.
diff --git a/plugins/tiddlywiki/markdown/frontmatter-serializer.js b/plugins/tiddlywiki/markdown/frontmatter-serializer.js
index 9750b1aeb..535b2afb6 100644
--- a/plugins/tiddlywiki/markdown/frontmatter-serializer.js
+++ b/plugins/tiddlywiki/markdown/frontmatter-serializer.js
@@ -32,7 +32,7 @@ var SKIP_FIELDS = {
 	revision: true
 };
 
-exports["text/x-markdown"] = function(tiddler) {
+function serialize(tiddler) {
 	if(!tiddler) {
 		return "";
 	}
@@ -72,4 +72,10 @@ exports["text/x-markdown"] = function(tiddler) {
 		return body;
 	}
 	return "---\n" + yaml.dump(frontmatter) + "\n---\n\n" + body;
-};
+}
+
+// Register under both types — text/markdown is what the "New Markdown" button
+// sets; text/x-markdown is what the deserializer uses after content-type
+// resolution for .md files loaded from disk.
+exports["text/x-markdown"] = serialize;
+exports["text/markdown"] = serialize;