diff --git a/dom/settings/SettingsManager.js b/dom/settings/SettingsManager.js
index 1edc16a7d19a..709ee406022f 100644
--- a/dom/settings/SettingsManager.js
+++ b/dom/settings/SettingsManager.js
@@ -88,10 +88,7 @@ SettingsLock.prototype = {
                 if (DEBUG) debug("store1: " + JSON.stringify(obj));
                 setReq = store.put(obj);
               } else {
-                //Workaround for cloning issues
-                let defaultVal = JSON.parse(JSON.stringify(defaultValue));
-                let userVal = JSON.parse(JSON.stringify(userValue));
-                let obj = {settingName: key, defaultValue: defaultVal, userValue: userVal};
+                let obj = {settingName: key, defaultValue: defaultValue, userValue: userValue};
                 if (DEBUG) debug("store2: " + JSON.stringify(obj));
                 setReq = store.put(obj);
               }
@@ -114,7 +111,7 @@ SettingsLock.prototype = {
                   Services.DOMRequest.fireError(request, setReq.error.name)
                 }
               };
-            }
+            };
             checkKeyRequest.onerror = function(event) {
               if (!request.error) {
                 Services.DOMRequest.fireError(request, checkKeyRequest.error.name)
@@ -127,8 +124,8 @@ SettingsLock.prototype = {
                                            : store.mozGetAll(info.name);
 
           getReq.onsuccess = function(event) {
-            if (DEBUG) debug("Request for '" + info.name + "' successful. " + 
-                  "Record count: " + event.target.result.length);
+            if (DEBUG) debug("Request for '" + info.name + "' successful. " +
+                             "Record count: " + event.target.result.length);
 
             if (event.target.result.length == 0) {
               if (DEBUG) debug("MOZSETTINGS-GET-WARNING: " + info.name + " is not in the database.\n");
@@ -214,8 +211,7 @@ SettingsLock.prototype = {
     if (this._settingsManager.hasWritePrivileges) {
       let req = Services.DOMRequest.createRequest(this._settingsManager._window);
       if (DEBUG) debug("send: " + JSON.stringify(aSettings));
-      let settings = JSON.parse(JSON.stringify(aSettings));
-      this._requests.enqueue({request: req, intent: "set", settings: settings});
+      this._requests.enqueue({request: req, intent: "set", settings: aSettings});
       this.createTransactionAndProcess();
       return req;
     } else {
@@ -312,7 +308,6 @@ SettingsManager.prototype = {
 
     switch (aMessage.name) {
       case "Settings:Change:Return:OK":
-        if (DEBUG) debug("Settings:Change:Return:OK");
         if (this._onsettingchange || this._callbacks) {
           if (DEBUG) debug('data:' + msg.key + ':' + msg.value + '\n');
 
@@ -334,7 +329,7 @@ SettingsManager.prototype = {
           if (DEBUG) debug("no observers stored!");
         }
         break;
-      default: 
+      default:
         if (DEBUG) debug("Wrong message: " + aMessage.name);
     }
   },
diff --git a/dom/settings/tests/Makefile.in b/dom/settings/tests/Makefile.in
index 032ffa43763b..739799ae5699 100644
--- a/dom/settings/tests/Makefile.in
+++ b/dom/settings/tests/Makefile.in
@@ -16,6 +16,7 @@ MOCHITEST_FILES = \
   test_settings_basics.html \
   test_settings_events.html \
   test_settings_onsettingchange.html \
+  test_settings_blobs.html \
   $(NULL)
 
 _CHROMEMOCHITEST_FILES = \
diff --git a/dom/settings/tests/test_settings_blobs.html b/dom/settings/tests/test_settings_blobs.html
new file mode 100644
index 000000000000..9a29a4500e9c
--- /dev/null
+++ b/dom/settings/tests/test_settings_blobs.html
@@ -0,0 +1,128 @@
+<!DOCTYPE html>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=821630
+-->
+<head>
+  <title>Test for Bug 821630 Settings API</title>
+  <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=821630">Mozilla Bug 821630</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript;version=1.8">
+
+"use strict";
+
+var comp = SpecialPowers.wrap(SpecialPowers.Components);
+comp.utils.import("resource://gre/modules/SettingsChangeNotifier.jsm");
+SpecialPowers.setBoolPref("dom.mozSettings.enabled", true);
+SpecialPowers.addPermission("settings-read", true, document);
+SpecialPowers.addPermission("settings-write", true, document);
+
+function onUnwantedSuccess() {
+  ok(false, "onUnwantedSuccess: shouldn't get here");
+}
+
+function onFailure() {
+  return function(s) {
+    if (s) {
+      ok(false, "in on Failure! - " + s);
+    } else {
+      ok(false, "in on Failure!");
+    }
+  }
+}
+
+let mozSettings = window.navigator.mozSettings;
+let req;
+
+let pageParts = ['<a id="a"><b id="b">hey!</b></a>'];
+let storedBlob = new Blob(pageParts, {"type": "text/xml"});
+
+function checkBlob(blob) {
+  try {
+    let url = URL.createObjectURL(blob);
+    ok(true, "Result is a blob");
+  } catch (e) {
+    ok(false, "Result is a blob");
+  }
+}
+
+let steps = [
+  function() {
+    let lock = mozSettings.createLock();
+    req = lock.clear();
+    req.onsuccess = next;
+    req.onerror = onFailure("Deleting database");
+  },
+  function() {
+    mozSettings.addObserver("test1", function(e) {
+      checkBlob(e.settingValue);
+      next();
+    });
+    next();
+  },
+  function() {
+    let lock = mozSettings.createLock();
+    // next is called by the observer above
+    req = lock.set({"test1": storedBlob});
+    req.onerror = onFailure("Saving blob");
+  },
+  function() {
+    let lock = mozSettings.createLock();
+    req = lock.get("test1");
+    req.onsuccess = function(event) {
+      checkBlob(event.target.result["test1"]);
+      next();
+    };
+    req.onerror = onFailure("Getting blob");
+  },
+  function() {
+    let lock = mozSettings.createLock();
+    req = lock.clear();
+    req.onsuccess = function() {
+      next();
+    };
+    req.onerror = onFailure("Deleting database");
+  },
+  function () {
+    ok(true, "all done!\n");
+    SimpleTest.finish();
+  }
+];
+
+function next() {
+  try {
+    let step = steps.shift();
+    if (step) {
+      step();
+    }
+  } catch(ex) {
+    ok(false, "Caught exception", ex);
+  }
+}
+
+function permissionTest() {
+  if (gSettingsEnabled) {
+    next();
+  } else {
+    is(mozSettings, null, "mozSettings is null when not enabled.");
+    SimpleTest.finish();
+  }
+}
+
+let gSettingsEnabled = SpecialPowers.getBoolPref("dom.mozSettings.enabled");
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(permissionTest);
+</script>
+</pre>
+</body>
+</html>
