diff --git a/CHANGELOG b/CHANGELOG
index 75dd48f..daefe8b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Prevent Hash#toQueryString from serializing objets. [kangax, Tobie Langel]
+
 * Fix Event#pointer in IE standard mode. Closes #9920. [kangax, Tobie Langel]
 
 * Instanciate Test.Unit.Logger on window load. [Tobie Langel]
diff --git a/src/hash.js b/src/hash.js
index b2d4872..125a96b 100644
--- a/src/hash.js
+++ b/src/hash.js
@@ -68,14 +68,14 @@ var Hash = Class.create(Enumerable, (function() {
     },
 
     toQueryString: function() {
-      return this.map(function(pair) {
+      return this.inject([], function(results, pair) {
         var key = encodeURIComponent(pair.key), values = pair.value;
 
         if (values && typeof values == 'object') {
           if (Object.isArray(values))
-            return values.map(toQueryPair.curry(key)).join('&');
-        }
-        return toQueryPair(key, values);
+            return results.concat(values.map(toQueryPair.curry(key)));
+        } else results.push(toQueryPair(key, values));
+        return results;
       }).join('&');
     },
 
diff --git a/test/unit/hash.html b/test/unit/hash.html
index d52ea9f..08ee58b 100644
--- a/test/unit/hash.html
+++ b/test/unit/hash.html
@@ -172,6 +172,7 @@
       this.assertEqual("color=r&color=&color=g&color&color=0", $H(Fixtures.multiple_nil).toQueryString());
       this.assertEqual("color=&color",       $H(Fixtures.multiple_all_nil).toQueryString());
       this.assertEqual("",                   $H(Fixtures.multiple_empty).toQueryString());
+      this.assertEqual("",                   $H({foo: {}, bar: {}}).toQueryString());
       this.assertEqual("stuff%5B%5D=%24&stuff%5B%5D=a&stuff%5B%5D=%3B", $H(Fixtures.multiple_special).toQueryString());
       this.assertHashEqual(Fixtures.multiple_special, $H(Fixtures.multiple_special).toQueryString().toQueryParams());
       this.assertIdentical(Object.toQueryString, Hash.toQueryString);