diff --git a/src/aphront/AphrontRequest.php b/src/aphront/AphrontRequest.php
--- a/src/aphront/AphrontRequest.php
+++ b/src/aphront/AphrontRequest.php
@@ -448,7 +448,7 @@
   }
 
   private function getPrefixedCookieName($name) {
-    if (strlen($this->cookiePrefix)) {
+    if (phutil_nonempty_string($this->cookiePrefix)) {
       return $this->cookiePrefix.'_'.$name;
     } else {
       return $name;
diff --git a/src/infrastructure/javelin/markup.php b/src/infrastructure/javelin/markup.php
--- a/src/infrastructure/javelin/markup.php
+++ b/src/infrastructure/javelin/markup.php
@@ -77,7 +77,10 @@
   $is_post = (strcasecmp($http_method, 'POST') === 0);
 
   $http_action = idx($attributes, 'action');
-  $is_absolute_uri = preg_match('#^(https?:|//)#', $http_action);
+  $is_absolute_uri = 0;
+  if (phutil_nonempty_string($http_action)) {
+    $is_absolute_uri = preg_match('#^(https?:|//)#', $http_action);
+  }
 
   if ($is_post) {