diff --git a/services/sync/modules/service.js b/services/sync/modules/service.js
index e01f332f8df8..3eb0bf5e1c5e 100644
--- a/services/sync/modules/service.js
+++ b/services/sync/modules/service.js
@@ -1317,8 +1317,6 @@ WeaveSvc.prototype = {
     // we'll handle that later
     Status.resetBackoff();
 
-    this.globalScore = 0;
-
     // Ping the server with a special info request once a day
     let infoURL = this.infoURL;
     let now = Math.floor(Date.now() / 1000);
@@ -1330,8 +1328,15 @@ WeaveSvc.prototype = {
 
     // Figure out what the last modified time is for each collection
     let info = new Resource(infoURL).get();
-    if (!info.success)
+    if (!info.success) {
+      if (info.status == 401) {
+        this.logout();
+        Status.login = LOGIN_FAILED_LOGIN_REJECTED;
+      }
       throw "aborting sync, failed to get collections";
+    }
+
+    this.globalScore = 0;
 
     // Convert the response to an object and read out the modified times
     for each (let engine in [Clients].concat(Engines.getAll()))
diff --git a/services/sync/tests/unit/test_service_sync_401.js b/services/sync/tests/unit/test_service_sync_401.js
new file mode 100644
index 000000000000..ab348dd0a321
--- /dev/null
+++ b/services/sync/tests/unit/test_service_sync_401.js
@@ -0,0 +1,71 @@
+Cu.import("resource://services-sync/service.js");
+
+function login_handler(request, response) {
+  // btoa('johndoe:ilovejane') == am9obmRvZTppbG92ZWphbmU=
+  let body;
+  if (request.hasHeader("Authorization") &&
+      request.getHeader("Authorization") == "Basic am9obmRvZTppbG92ZWphbmU=") {
+    body = "{}";
+    response.setStatusLine(request.httpVersion, 200, "OK");
+  } else {
+    body = "Unauthorized";
+    response.setStatusLine(request.httpVersion, 401, "Unauthorized");
+  }
+  response.bodyOutputStream.write(body, body.length);
+}
+
+function run_test() {
+  let logger = Log4Moz.repository.rootLogger;
+  Log4Moz.repository.rootLogger.addAppender(new Log4Moz.DumpAppender());
+
+  do_test_pending();
+  let server = httpd_setup({
+    "/1.0/johndoe/info/collections": login_handler
+  });
+
+  const GLOBAL_SCORE = 42;
+
+  try {
+    _("Set up test fixtures.");
+    Weave.Service.serverURL = "http://localhost:8080/";
+    Weave.Service.clusterURL = "http://localhost:8080/";
+    Weave.Service.username = "johndoe";
+    Weave.Service.password = "ilovejane";
+    Weave.Service.passphrase = "foo";
+    Weave.Service.globalScore = GLOBAL_SCORE;
+    // Avoid daily ping
+    Weave.Svc.Prefs.set("lastPing", Math.floor(Date.now() / 1000));
+
+    let threw = false;
+    Weave.Svc.Obs.add("weave:service:sync:error", function (subject, data) {
+      threw = true;
+    });
+
+    _("Initial state: We're successfully logged in.");
+    Weave.Service.login();
+    do_check_true(Weave.Service.isLoggedIn);
+    do_check_eq(Weave.Status.login, Weave.LOGIN_SUCCEEDED);
+
+    _("Simulate having changed the password somehwere else.");
+    Weave.Service.password = "ilovejosephine";
+
+    _("Let's try to sync.");
+    Weave.Service.sync();
+
+    _("Verify that sync() threw an exception.");
+    do_check_true(threw);
+
+    _("We're no longer logged in.");
+    do_check_false(Weave.Service.isLoggedIn);
+
+    _("Sync status.");
+    do_check_eq(Weave.Status.login, Weave.LOGIN_FAILED_LOGIN_REJECTED);
+
+    _("globalScore is unchanged.");
+    do_check_eq(Weave.Service.globalScore, GLOBAL_SCORE);
+
+  } finally {
+    Weave.Svc.Prefs.resetBranch("");
+    server.stop(do_test_finished);
+  }
+}