Fix E_NOTICE in `add_handler()`.

1 files changed, 1 insertions, 1 deletions

diff --git a/classes/pluginhost.php b/classes/pluginhost.php
index 17d1e0c5f..6fbc13a9c 100755
--- a/classes/pluginhost.php
+++ b/classes/pluginhost.php
@@ -352,7 +352,7 @@ class PluginHost {
 		$method = strtolower($method);
 
 		if ($this->is_system($sender)) {
-			if (!is_array($this->handlers[$handler])) {
+			if (!isset($this->handlers[$handler])) {
 				$this->handlers[$handler] = array();
 			}