diff --git a/src/applications/auth/constants/PhabricatorCookies.php b/src/applications/auth/constants/PhabricatorCookies.php
--- a/src/applications/auth/constants/PhabricatorCookies.php
+++ b/src/applications/auth/constants/PhabricatorCookies.php
@@ -89,7 +89,7 @@
     // temporary and clearing it when users log out.
 
     $value = $request->getCookie(self::COOKIE_CLIENTID);
-    if (!strlen($value)) {
+    if (!phutil_nonempty_string($value)) {
       $request->setTemporaryCookie(
         self::COOKIE_CLIENTID,
         Filesystem::readRandomCharacters(16));
diff --git a/src/applications/auth/controller/PhabricatorAuthController.php b/src/applications/auth/controller/PhabricatorAuthController.php
--- a/src/applications/auth/controller/PhabricatorAuthController.php
+++ b/src/applications/auth/controller/PhabricatorAuthController.php
@@ -282,7 +282,7 @@
       $viewer,
       PhabricatorAuthLoginMessageType::MESSAGEKEY);
 
-    if (!strlen($text)) {
+    if (!phutil_nonempty_string($text)) {
       return null;
     }
 
diff --git a/src/applications/auth/controller/PhabricatorAuthStartController.php b/src/applications/auth/controller/PhabricatorAuthStartController.php
--- a/src/applications/auth/controller/PhabricatorAuthStartController.php
+++ b/src/applications/auth/controller/PhabricatorAuthStartController.php
@@ -98,7 +98,7 @@
     }
 
     $next_uri = $request->getStr('next');
-    if (!strlen($next_uri)) {
+    if (!phutil_nonempty_string($next_uri)) {
       if ($this->getDelegatingController()) {
         // Only set a next URI from the request path if this controller was
         // delegated to, which happens when a user tries to view a page which
@@ -112,7 +112,7 @@
     }
 
     if (!$request->isFormPost()) {
-      if (strlen($next_uri)) {
+      if (phutil_nonempty_string($next_uri)) {
         PhabricatorCookies::setNextURICookie($request, $next_uri);
       }
       PhabricatorCookies::setClientIDCookie($request);