diff --git a/packages/showdown/template-integration.js b/packages/showdown/template-integration.js
index d5fcd5713e..b4bef234c0 100644
--- a/packages/showdown/template-integration.js
+++ b/packages/showdown/template-integration.js
@@ -4,7 +4,7 @@ if (Package.ui) {
   Package.ui.Handlebars.registerHelper('markdown', UI.block(function () {
     var self = this;
     return function () {
-      var text = UI.toRawText(self.__content);
+      var text = UI.toRawText(self.__content, self /*parentComponent*/);
       var converter = new Showdown.converter();
       return HTML.Raw(converter.makeHtml(text));
     };
diff --git a/packages/spacebars-tests/template_tests.html b/packages/spacebars-tests/template_tests.html
index a9507f0bc3..e412ec0d38 100644
--- a/packages/spacebars-tests/template_tests.html
+++ b/packages/spacebars-tests/template_tests.html
@@ -288,7 +288,8 @@
 </template>
 
 <template name="spacebars_template_test_markdown_basic">
-  {{#markdown}}
+  {{#with obj}}
+    {{#markdown}}
 {{hi}}
 /each}}
 
@@ -301,20 +302,28 @@
 * <b>{{hi}}</b>
 * <b>/each}}</b>
 
+some paragraph to fix showdown's four space parsing below.
+
     {{hi}}
     /each}}
 
     <b>{{hi}}</b>
-    <b>/each</b>
+    <b>/each}}</b>
 
 &gt
+
 * &gt
+
 `&gt`
+
     &gt
 
 &gt;
+
 * &gt;
+
 `&gt;`
+
     &gt;
 
 `{{hi}}`
@@ -323,19 +332,29 @@
 `<b>{{hi}}</b>`
 `<b>/each}}`
 
-  {{/markdown}}
+    {{/markdown}}
+  {{/with}}
 </template>
 
 <template name="spacebars_template_test_markdown_if">
   {{#markdown}}
 
 {{#if cond}}true{{else}}false{{/if}}
+
 <b>{{#if cond}}true{{else}}false{{/if}}</b>
+
 * {{#if cond}}true{{else}}false{{/if}}
+
 * <b>{{#if cond}}true{{else}}false{{/if}}</b>
+
+some paragraph to fix showdown's four space parsing below.
+
     {{#if cond}}true{{else}}false{{/if}}
+
     <b>{{#if cond}}true{{else}}false{{/if}}</b>
+
 `{{#if cond}}true{{else}}false{{/if}}`
+
 `<b>{{#if cond}}true{{else}}false{{/if}}</b>`
 
   {{/markdown}}
@@ -345,12 +364,21 @@
   {{#markdown}}
 
 {{#each seq}}{{.}}{{/each}}
+
 <b>{{#each seq}}{{.}}{{/each}}</b>
+
 * {{#each seq}}{{.}}{{/each}}
+
 * <b>{{#each seq}}{{.}}{{/each}}</b>
+
+some paragraph to fix showdown's four space parsing below.
+
     {{#each seq}}{{.}}{{/each}}
+
     <b>{{#each seq}}{{.}}{{/each}}</b>
+
 `{{#each seq}}{{.}}{{/each}}`
+
 `<b>{{#each seq}}{{.}}{{/each}}</b>`
 
   {{/markdown}}
diff --git a/packages/spacebars-tests/template_tests.js b/packages/spacebars-tests/template_tests.js
index ec0bd8f157..cfa5540ef2 100644
--- a/packages/spacebars-tests/template_tests.js
+++ b/packages/spacebars-tests/template_tests.js
@@ -946,16 +946,76 @@ Tinytest.add('spacebars - templates - constant #each argument', function (test)
 // @returns {String} simplified html content
 var divContentForMarkdown = function (div) {
   return trim(stripComments(div.innerHTML))
-        .replace(/\<br\>/g, '\n');
+        .replace(/\<br\>/g, '\n')
+        .replace(/<(\/?\S+)>/g, function (s) { return s.toLowerCase(); }); // for IE
+};
+
+// extract a multi-line string from a comment within a function.
+// @param f {Function} eg function () { /* [[[...content...]]] */ }
+// @returns {String} eg "content"
+var textFromFunction = function(f) {
+  return f.toString().match(/\[\[\[([\S\s]*)\]\]\]/m)[1]
+    .replace(/[ ]*\/\/ \d+$/gm, ''); // remove line number comments
 };
 
 Tinytest.add('spacebars - templates - #markdown - basic', function (test) {
   var tmpl = Template.spacebars_template_test_markdown_basic;
+  tmpl.obj = {snippet: "<i>hi</i>"};
   tmpl.hi = function () {
-    return "<i>hi</i>";
+    return this.snippet;
   };
   var div = renderToDiv(tmpl);
-  test.equal(divContentForMarkdown(div), "FIXME");
+  test.equal(divContentForMarkdown(div), textFromFunction(function () { /*
+[[[<p><i>hi</i>
+/each}}</p>
+
+<p><b><i>hi</i></b>
+<b>/each}}</b></p>
+
+<ul>
+<li><i>hi</i></li>
+<li><p>/each}}</p></li>
+<li><p><b><i>hi</i></b></p></li>
+<li><b>/each}}</b></li>
+</ul>
+
+<p>some paragraph to fix showdown's four space parsing below.</p>
+
+<pre><code>&lt;i&gt;hi&lt;/i&gt;
+/each}}
+
+&lt;b&gt;&lt;i&gt;hi&lt;/i&gt;&lt;/b&gt;
+&lt;b&gt;/each}}&lt;/b&gt;
+</code></pre>
+
+<p>&amp;gt</p>
+
+<ul>
+<li>&amp;gt</li>
+</ul>
+
+<p><code>&amp;gt</code></p>
+
+<pre><code>&amp;gt
+</code></pre>
+
+<p>&gt;</p>
+
+<ul>
+<li>&gt;</li>
+</ul>
+
+<p><code>&amp;gt;</code></p>
+
+<pre><code>&amp;gt;
+</code></pre>
+
+<p><code>&lt;i&gt;hi&lt;/i&gt;</code>
+<code>/each}}</code></p>
+
+<p><code>&lt;b&gt;&lt;i&gt;hi&lt;/i&gt;&lt;/b&gt;</code>
+<code>&lt;b&gt;/each}}</code></p>]]] */
+  }));
 });
 
 Tinytest.add('spacebars - templates - #markdown - if', function (test) {
@@ -964,10 +1024,50 @@ Tinytest.add('spacebars - templates - #markdown - if', function (test) {
   tmpl.cond = function () { return R.get(); };
 
   var div = renderToDiv(tmpl);
-  test.equal(divContentForMarkdown(div), "FIXME(false)");
+  test.equal(divContentForMarkdown(div), textFromFunction(function () { /*
+[[[<p>false</p>
+
+<p><b>false</b></p>
+
+<ul>
+<li><p>false</p></li>
+<li><p><b>false</b></p></li>
+</ul>
+
+<p>some paragraph to fix showdown's four space parsing below.</p>
+
+<pre><code>false
+
+&lt;b&gt;false&lt;/b&gt;
+</code></pre>
+
+<p><code>false</code></p>
+
+<p><code>&lt;b&gt;false&lt;/b&gt;</code></p>]]] */
+  }));
   R.set(true);
   Deps.flush();
-  test.equal(divContentForMarkdown(div), "FIXME(true)");
+  test.equal(divContentForMarkdown(div), textFromFunction(function () { /*
+[[[<p>true</p>
+
+<p><b>true</b></p>
+
+<ul>
+<li><p>true</p></li>
+<li><p><b>true</b></p></li>
+</ul>
+
+<p>some paragraph to fix showdown's four space parsing below.</p>
+
+<pre><code>true
+
+&lt;b&gt;true&lt;/b&gt;
+</code></pre>
+
+<p><code>true</code></p>
+
+<p><code>&lt;b&gt;true&lt;/b&gt;</code></p>]]] */
+  }));
 });
 
 Tinytest.add('spacebars - templates - #markdown - each', function (test) {
@@ -976,10 +1076,47 @@ Tinytest.add('spacebars - templates - #markdown - each', function (test) {
   tmpl.seq = function () { return R.get(); };
 
   var div = renderToDiv(tmpl);
-  test.equal(divContentForMarkdown(div), "FIXME([])");
+  test.equal(divContentForMarkdown(div), textFromFunction(function () { /*
+[[[<p><b></b></p>
+
+<ul>
+<li></li>
+<li><b></b></li>
+</ul>
+
+<p>some paragraph to fix showdown's four space parsing below.</p>
+
+<pre><code>&lt;b&gt;&lt;/b&gt;
+</code></pre>
+
+<p>``</p>
+
+<p><code>&lt;b&gt;&lt;/b&gt;</code></p>]]] */
+    }));
+
   R.set(["item"]);
   Deps.flush();
-  test.equal(divContentForMarkdown(div), "FIXME([\"item\"])");
+  test.equal(divContentForMarkdown(div), textFromFunction(function () { /*
+[[[<p>item</p>
+
+<p><b>item</b></p>
+
+<ul>
+<li><p>item</p></li>
+<li><p><b>item</b></p></li>
+</ul>
+
+<p>some paragraph to fix showdown's four space parsing below.</p>
+
+<pre><code>item
+
+&lt;b&gt;item&lt;/b&gt;
+</code></pre>
+
+<p><code>item</code></p>
+
+<p><code>&lt;b&gt;item&lt;/b&gt;</code></p>]]] */
+    }));
 });
 
 Tinytest.add('spacebars - templates - #markdown - inclusion', function (test) {
diff --git a/packages/ui/components.js b/packages/ui/components.js
index ac42dc35ac..9ffff780e9 100644
--- a/packages/ui/components.js
+++ b/packages/ui/components.js
@@ -12,7 +12,7 @@ UI.If = Component.extend({
     // of a Component during init (but presumably not before
     // or after)?
   },
-  render: function (buf) {
+  render: function () {
     var self = this;
     return function () {
       var condition = getCondition(self);
@@ -54,7 +54,7 @@ UI.Unless = Component.extend({
     this.condition = this.data;
     this.data = undefined;
   },
-  render: function (buf) {
+  render: function () {
     var self = this;
     return function () {
       var condition = getCondition(self);
@@ -68,7 +68,7 @@ UI.With = Component.extend({
   init: function () {
     this.condition = this.data;
   },
-  render: function (buf) {
+  render: function () {
     var self = this;
     return function () {
       var condition = getCondition(self);