diff --git a/src/mibew/libs/classes/Mibew/Button/Generator/AbstractGenerator.php b/src/mibew/libs/classes/Mibew/Button/Generator/AbstractGenerator.php
index 3635cf20..e2ee743d 100644
--- a/src/mibew/libs/classes/Mibew/Button/Generator/AbstractGenerator.php
+++ b/src/mibew/libs/classes/Mibew/Button/Generator/AbstractGenerator.php
@@ -178,8 +178,8 @@ abstract class AbstractGenerator implements GeneratorInterface
 
         return sprintf(
             "toolbar=0,scrollbars=0,location=0,status=1,menubar=0,width=%u,height=%u,resizable=%u",
-            $chat_configurations['chat']['window']['width'],
-            $chat_configurations['chat']['window']['height'],
+            $chat_configurations['chat']['window']['width'] ?: 640,
+            $chat_configurations['chat']['window']['height'] ?: 480,
             $chat_configurations['chat']['window']['resizable'] ? '1' : '0'
         );
     }
diff --git a/src/mibew/libs/classes/Mibew/Style/ChatStyle.php b/src/mibew/libs/classes/Mibew/Style/ChatStyle.php
index f02c3c7c..87452be2 100644
--- a/src/mibew/libs/classes/Mibew/Style/ChatStyle.php
+++ b/src/mibew/libs/classes/Mibew/Style/ChatStyle.php
@@ -141,18 +141,10 @@ class ChatStyle extends AbstractHandlebarsPoweredStyle implements StyleInterface
     {
         return array(
             'chat' => array(
-                'window' => array(
-                    'width' => 640,
-                    'height' => 480,
-                    'resizable' => true,
-                ),
+                'window' => array(),
             ),
             'mail' => array(
-                'window' => array(
-                    'width' => 640,
-                    'height' => 480,
-                    'resizable' => true,
-                ),
+                'window' => array(),
             ),
             'screenshots' => array(),
         );