diff --git a/packages/test-helpers/canonicalize_html.js b/packages/test-helpers/canonicalize_html.js
index ba1868d0a3..9f6d369a78 100644
--- a/packages/test-helpers/canonicalize_html.js
+++ b/packages/test-helpers/canonicalize_html.js
@@ -31,12 +31,15 @@ canonicalizeHtml = function(html) {
     attrs = attrs.replace(/\s+/g, ' ');
     // quote unquoted attribute values, as in `type=checkbox`.  This
     // will do the wrong thing if there's an `=` in an attribute value.
-    attrs = attrs.replace(/(\w)=([^" >/]+)/g, '$1="$2"');
-    // for the purpose of splitting attributes in a string like
-    // 'a="b" c="d"', assume they are separated by a single space
-    // and values are double-quoted, but allow for spaces inside
-    // the quotes.  Split on space following quote.
-    var attrList = attrs.replace(/" /g, '"\u0000').split('\u0000');
+    attrs = attrs.replace(/(\w)=([^'" >/]+)/g, '$1="$2"');
+
+    // for the purpose of splitting attributes in a string like 'a="b"
+    // c="d"', assume they are separated by a single space and values
+    // are double- or single-quoted, but allow for spaces inside the
+    // quotes.  Split on space following quote.
+    var attrList = attrs.replace(/(\w)='([^']+)' /g, "$1='$2'\u0000");
+    attrList = attrList.replace(/(\w)="([^"]+)" /g, '$1="$2"\u0000');
+    attrList = attrList.split("\u0000");
     // put attributes in alphabetical order
     attrList.sort();
 
@@ -59,11 +62,21 @@ canonicalizeHtml = function(html) {
       if (key === 'sizset')
         continue;
       var value = a[1];
-      value = value.replace(/["'`]/g, '"');
-      // this check is probably made unreachable by a regex above
-      // that quotes unquoted attribute values
-      if (value.charAt(0) !== '"')
-        value = '"'+value+'"';
+
+      // make sure the attribute is doubled-quoted
+      if (value.charAt(0) === '"') {
+        // Do nothing
+      } else {
+        if (value.charAt(0) !== "'") {
+          // attribute is unquoted. should be unreachable because of
+          // regex above.
+          value = '"' + value + '"';
+        } else {
+          // attribute is single-quoted. make it double-quoted.
+          value = value.replace(/\"/g, """);
+        }
+        value = value.replace(/["'`]/g, '"');
+      }
       tagContents.push(key+'='+value);
     }
     return '<'+tagContents.join(' ')+'>';
diff --git a/packages/ui/render_tests.js b/packages/ui/render_tests.js
index 3c0ac08834..b2599ec647 100644
--- a/packages/ui/render_tests.js
+++ b/packages/ui/render_tests.js
@@ -271,18 +271,18 @@ Tinytest.add("ui - render - reactive attributes", function (test) {
   // Test styles.
   (function () {
     // Test the case where there is a semicolon in the css attribute.
-    var R = ReactiveVar({'style': 'foo:"a;aa"; bar: b;',
+    var R = ReactiveVar({'style': 'foo: "a;aa"; bar: b;',
       id: 'foo'});
 
     var spanCode = SPAN({$dynamic: [function () { return R.get(); }]});
 
-    test.equal(toHTML(spanCode), '<span style="foo:&quot;a;aa&quot;; bar: b;" id="foo"></span>');
+    test.equal(toHTML(spanCode), '<span style="foo: &quot;a;aa&quot;; bar: b;" id="foo"></span>');
 
     test.equal(R.numListeners(), 0);
 
     var div = document.createElement("DIV");
     materialize(spanCode, div);
-    test.equal(canonicalizeHtml(div.innerHTML), '<span id="foo" style="foo:&quot;a;aa&quot;; bar: b;"></span>');
+    test.equal(canonicalizeHtml(div.innerHTML), '<span id="foo" style="foo: &quot;a;aa&quot;; bar: b;"></span>');
 
     test.equal(R.numListeners(), 1);
 
@@ -292,7 +292,7 @@ Tinytest.add("ui - render - reactive attributes", function (test) {
 
     R.set({'style': 'foo:"a;zz;aa"', id: 'bar'});
     Deps.flush();
-    test.equal(canonicalizeHtml(div.innerHTML), '<span id="bar" style="jquery-style: hidden; foo:&quot;a;zz;aa&quot;"></span>');
+    test.equal(canonicalizeHtml(div.innerHTML, true), '<span id="bar" style="jquery-style: hidden; foo:&quot;a;zz;aa&quot;"></span>');
     test.equal(R.numListeners(), 1);
 
     R.set({});
@@ -675,4 +675,4 @@ Tinytest.add("ui - UI.render _nestInCurrentComputation flag", function (test) {
       test.equal(firstComputation.stopped, false);
     }
   });
-});
\ No newline at end of file
+});