diff --git a/src/applications/diffusion/controller/DiffusionRepositoryManagePanelsController.php b/src/applications/diffusion/controller/DiffusionRepositoryManagePanelsController.php
--- a/src/applications/diffusion/controller/DiffusionRepositoryManagePanelsController.php
+++ b/src/applications/diffusion/controller/DiffusionRepositoryManagePanelsController.php
@@ -40,7 +40,7 @@
     }
 
     $selected = $request->getURIData('panel');
-    if (!strlen($selected)) {
+    if (!phutil_nonempty_string($selected)) {
       $selected = head_key($panels);
     }
 
diff --git a/src/applications/diffusion/controller/DiffusionServeController.php b/src/applications/diffusion/controller/DiffusionServeController.php
--- a/src/applications/diffusion/controller/DiffusionServeController.php
+++ b/src/applications/diffusion/controller/DiffusionServeController.php
@@ -43,8 +43,8 @@
       return null;
     }
 
-    $content_type = $request->getHTTPHeader('Content-Type');
-    $user_agent = idx($_SERVER, 'HTTP_USER_AGENT');
+    $content_type = $request->getHTTPHeader('Content-Type', '');
+    $user_agent = idx($_SERVER, 'HTTP_USER_AGENT', '');
     $request_type = $request->getHTTPHeader('X-Phabricator-Request-Type');
 
     // This may have a "charset" suffix, so only match the prefix.
diff --git a/src/applications/diffusion/management/DiffusionRepositoryBasicsManagementPanel.php b/src/applications/diffusion/management/DiffusionRepositoryBasicsManagementPanel.php
--- a/src/applications/diffusion/management/DiffusionRepositoryBasicsManagementPanel.php
+++ b/src/applications/diffusion/management/DiffusionRepositoryBasicsManagementPanel.php
@@ -219,7 +219,7 @@
     $view->addProperty(pht('Type'), $type);
 
     $callsign = $repository->getCallsign();
-    if (!strlen($callsign)) {
+    if (!phutil_nonempty_string($callsign)) {
       $callsign = phutil_tag('em', array(), pht('No Callsign'));
     }
     $view->addProperty(pht('Callsign'), $callsign);
diff --git a/src/applications/repository/editor/PhabricatorRepositoryEditor.php b/src/applications/repository/editor/PhabricatorRepositoryEditor.php
--- a/src/applications/repository/editor/PhabricatorRepositoryEditor.php
+++ b/src/applications/repository/editor/PhabricatorRepositoryEditor.php
@@ -50,7 +50,7 @@
     // If the repository does not have a local path yet, assign it one based
     // on its ID. We can't do this earlier because we won't have an ID yet.
     $local_path = $object->getLocalPath();
-    if (!strlen($local_path)) {
+    if (!phutil_nonempty_string($local_path)) {
       $local_key = 'repository.default-local-path';
 
       $local_root = PhabricatorEnv::getEnvConfig($local_key);