diff --git a/wire/core/ProcessWire.php b/wire/core/ProcessWire.php
index fe1afb97..1146ed1a 100644
--- a/wire/core/ProcessWire.php
+++ b/wire/core/ProcessWire.php
@@ -258,7 +258,7 @@ class ProcessWire extends Wire {
 		}
 		
 		$config->ajax = (isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest');
-		$config->cli = (!isset($_SERVER['SERVER_SOFTWARE']) && (php_sapi_name() == 'cli' || ($_SERVER['argc'] > 0 && is_numeric($_SERVER['argc']))));
+		$config->cli = (!isset($_SERVER['SERVER_SOFTWARE']) && (php_sapi_name() == 'cli' || (isset($_SERVER['argc']) && $_SERVER['argc'] > 0 && is_numeric($_SERVER['argc']))));
 		$config->modal = empty($_GET['modal']) ? false : abs((int) $_GET['modal']); 
 		
 		$version = self::versionMajor . "." . self::versionMinor . "." . self::versionRevision;