diff --git a/net/instaweb/config/measurement_proxy_rewrite_options_manager_test.cc b/net/instaweb/config/measurement_proxy_rewrite_options_manager_test.cc
index d76c4a077..009ad7eae 100644
--- a/net/instaweb/config/measurement_proxy_rewrite_options_manager_test.cc
+++ b/net/instaweb/config/measurement_proxy_rewrite_options_manager_test.cc
@@ -47,7 +47,8 @@ class MeasurementProxyRewriteOptionsManagerTest
     ProxyInterfaceTestBase::SetUp();
     options_manager_ = new MeasurementProxyRewriteOptionsManager(
         server_context(), "https://www.example.com", "secret");
-    url_namer_.reset(new MeasurementProxyUrlNamer());
+    url_namer_.reset(new MeasurementProxyUrlNamer(
+        "https://www.example.com", "secret"));
     server_context()->SetRewriteOptionsManager(options_manager_);
     server_context()->set_url_namer(url_namer_.get());
   }
diff --git a/net/instaweb/rewriter/measurement_proxy_url_namer.cc b/net/instaweb/rewriter/measurement_proxy_url_namer.cc
index d7abf157a..bfe052990 100644
--- a/net/instaweb/rewriter/measurement_proxy_url_namer.cc
+++ b/net/instaweb/rewriter/measurement_proxy_url_namer.cc
@@ -27,7 +27,12 @@
 namespace net_instaweb {
 
 
-MeasurementProxyUrlNamer::MeasurementProxyUrlNamer() {
+MeasurementProxyUrlNamer::MeasurementProxyUrlNamer(
+    const GoogleString& top_origin, const GoogleString& password)
+    : top_origin_(top_origin), password_(password) {
+  if (StringPiece(top_origin_).ends_with("/")) {
+    top_origin_.resize(top_origin.size() - 1);
+  }
 }
 
 MeasurementProxyUrlNamer::~MeasurementProxyUrlNamer() {
diff --git a/net/instaweb/rewriter/measurement_proxy_url_namer_test.cc b/net/instaweb/rewriter/measurement_proxy_url_namer_test.cc
index 2dc00a565..9f4afd6d2 100644
--- a/net/instaweb/rewriter/measurement_proxy_url_namer_test.cc
+++ b/net/instaweb/rewriter/measurement_proxy_url_namer_test.cc
@@ -33,6 +33,7 @@ namespace net_instaweb {
 
 class MeasurementProxyUrlNamerTest : public RewriteTestBase {
  protected:
+  MeasurementProxyUrlNamerTest() : namer_("http://www.example.com/", "pwd") {}
   MeasurementProxyUrlNamer namer_;
 };
 
diff --git a/net/instaweb/rewriter/public/measurement_proxy_url_namer.h b/net/instaweb/rewriter/public/measurement_proxy_url_namer.h
index c6d42fa8b..471a8430b 100644
--- a/net/instaweb/rewriter/public/measurement_proxy_url_namer.h
+++ b/net/instaweb/rewriter/public/measurement_proxy_url_namer.h
@@ -38,12 +38,10 @@ class RewriteOptions;
 // before fetching via us (as this doesn't implement Encode() itself).
 class MeasurementProxyUrlNamer : public UrlNamer {
  public:
-  MeasurementProxyUrlNamer();
+  MeasurementProxyUrlNamer(const GoogleString& top_origin,
+                           const GoogleString& password);
   ~MeasurementProxyUrlNamer() override;
 
-  // Note: this doesn't deal with the authenication or verification
-  // of origin or password, the MeasurementProxyRewriteOptionsManager is
-  // expected to do that.
   bool Decode(const GoogleUrl& request_url,
               const RewriteOptions* rewrite_options,
               GoogleString* decoded) const override;
@@ -61,6 +59,9 @@ class MeasurementProxyUrlNamer : public UrlNamer {
   }
 
  private:
+  GoogleString top_origin_;
+  GoogleString password_;
+
   DISALLOW_COPY_AND_ASSIGN(MeasurementProxyUrlNamer);
 };
 
diff --git a/pagespeed/apache/apache_server_context.cc b/pagespeed/apache/apache_server_context.cc
index 5d20f6030..6685ec0fb 100644
--- a/pagespeed/apache/apache_server_context.cc
+++ b/pagespeed/apache/apache_server_context.cc
@@ -162,7 +162,9 @@ void ApacheServerContext::ChildInit(SystemRewriteDriverFactory* f) {
   if (global_config()->proxy_all_requests_mode()) {
     apache_factory_->SetNeedSchedulerThread();
     if (global_config()->measurement_proxy_mode()) {
-      measurement_url_namer_.reset(new MeasurementProxyUrlNamer());
+      measurement_url_namer_.reset(new MeasurementProxyUrlNamer(
+          global_config()->measurement_proxy_root(),
+          global_config()->measurement_proxy_password()));
       set_url_namer(measurement_url_namer_.get());
       SetRewriteOptionsManager(new MeasurementProxyRewriteOptionsManager(
           this,