diff --git a/calendar/inc/class.uiforms.inc.php b/calendar/inc/class.uiforms.inc.php
index 478f680aae..467bd6d073 100644
--- a/calendar/inc/class.uiforms.inc.php
+++ b/calendar/inc/class.uiforms.inc.php
@@ -1220,7 +1220,7 @@ class uiforms extends uical
 			else
 			{
 				$GLOBALS['egw']->browser =& CreateObject('phpgwapi.browser');
-				$GLOBALS['egw']->browser->content_header('event.ics','text/calendar',strlen($ical));
+				$GLOBALS['egw']->browser->content_header('event.ics','text/calendar',bytes($ical));
 				echo $ical;
 				$GLOBALS['egw']->common->egw_exit();
 			}
@@ -1243,7 +1243,7 @@ class uiforms extends uical
 			{
 				$ical =& ExecMethod2('calendar.boical.exportVCal',$events,'2.0'/*$content['version']*/);
 				$GLOBALS['egw']->browser =& CreateObject('phpgwapi.browser');
-				$GLOBALS['egw']->browser->content_header($content['file'] ? $content['file'] : 'event.ics','text/calendar',strlen($ical));
+				$GLOBALS['egw']->browser->content_header($content['file'] ? $content['file'] : 'event.ics','text/calendar',bytes($ical));
 				echo $ical;
 				$GLOBALS['egw']->common->egw_exit();
 			}
diff --git a/phpgwapi/inc/class.db_backup.inc.php b/phpgwapi/inc/class.db_backup.inc.php
index eaac7732c4..10ad6280aa 100644
--- a/phpgwapi/inc/class.db_backup.inc.php
+++ b/phpgwapi/inc/class.db_backup.inc.php
@@ -438,7 +438,7 @@
 				{
 					$this->browser = CreateObject('phpgwapi.browser');
 				}
-				$this->browser->content_header('schema-backup-'.date('YmdHi').'.inc.php','text/plain',strlen($def));
+				$this->browser->content_header('schema-backup-'.date('YmdHi').'.inc.php','text/plain',bytes($def));
 				echo "<?php\n\t/* eGroupWare schema-backup from ".date('Y-m-d H:i:s')." */\n\n".$def;
 			}
 		}
diff --git a/phpgwapi/inc/class.http.inc.php b/phpgwapi/inc/class.http.inc.php
index 8d5dabc010..7324072b8e 100644
--- a/phpgwapi/inc/class.http.inc.php
+++ b/phpgwapi/inc/class.http.inc.php
@@ -286,7 +286,7 @@
 			}
 			if(($success = $this->PutLine($this->request_method.' '.$request_uri.' HTTP/'.$this->protocol_version)))
 			{
-				if(($body_length = strlen($request_body)))
+				if(($body_length = bytes($request_body)))
 				{
 					$headers['Content-length'] = $body_length;
 				}
diff --git a/phpgwapi/inc/class.xmlrpc_server_epi.inc.php b/phpgwapi/inc/class.xmlrpc_server_epi.inc.php
index 547f922d1e..6cc0c8166d 100644
--- a/phpgwapi/inc/class.xmlrpc_server_epi.inc.php
+++ b/phpgwapi/inc/class.xmlrpc_server_epi.inc.php
@@ -60,7 +60,7 @@
 			else
 			{
 //				$payload = '<?xml version="1.0"?\>' . "\n" . $this->serializeDebug() . $r->serialize();
-//				Header("Content-type: text/xml\r\nContent-length: " . strlen($payload));
+//				Header("Content-type: text/xml\r\nContent-length: " . bytes($payload));
 //				print $payload;
 				echo $r;
 			}
diff --git a/phpgwapi/inc/class.xmlrpc_server_php.inc.php b/phpgwapi/inc/class.xmlrpc_server_php.inc.php
index b01c2a54dc..18575dd742 100644
--- a/phpgwapi/inc/class.xmlrpc_server_php.inc.php
+++ b/phpgwapi/inc/class.xmlrpc_server_php.inc.php
@@ -95,7 +95,7 @@
 				$payload = $GLOBALS['egw']->translation->convert("<?xml version=\"1.0\"?>\n" . $this->serializeDebug() . $r->serialize(),
 					$GLOBALS['egw']->translation->charset(),'utf-8');
 				header("Content-type: text/xml");
-				header("Content-length: " . $this->bytes($payload));
+				header("Content-length: " . bytes($payload));
 				echo $payload;
 			}
 
@@ -121,24 +121,6 @@
 			}
 		}
 		
-		/**
-		 * mbstring.func_overload save strlen version: counting the bytes not the chars
-		 *
-		 * @param string $str
-		 * @return int
-		 */
-		function bytes($str)
-		{
-			static $func_overload;
-
-			if (is_null($func_overload))
-			{
-				$func_overload = @extension_loaded('mbstring') ? ini_get('mbstring.func_overload') : 0;
-			}
-			return $func_overload & 2 ? mb_strlen($str,'ascii') : strlen($str);
-		}
-		
-
 		/*
 		 * add a method to the dispatch map
 		 */
diff --git a/phpgwapi/inc/common_functions.inc.php b/phpgwapi/inc/common_functions.inc.php
index b50c10149f..708cac8fe3 100755
--- a/phpgwapi/inc/common_functions.inc.php
+++ b/phpgwapi/inc/common_functions.inc.php
@@ -28,6 +28,22 @@
 	 * because they are required to be available at the lowest level.            *
 	 \***************************************************************************/
 
+	/**
+	 * Return the number of bytes of a string, independent of mbstring.func_overload
+	 * AND the availability of mbstring
+	 *
+	 * @param string $str
+	 * @return int
+	 */
+	function bytes($str)
+	{
+		static $func_overload;
+		
+		if (is_null($func_overload)) $func_overload = extension_loaded('mbstring') ? ini_get('mbstring.func_overload') : 0;
+		
+		return $func_overload & 2 ? mb_strlen($str,'ascii') : strlen($str);
+	}
+
 	/**
 	 * @internal Not to be used directly. Should only be used by print_debug()
 	 */
diff --git a/phpgwapi/inc/xml_functions.inc.php b/phpgwapi/inc/xml_functions.inc.php
index 58b35b4f12..b400043074 100644
--- a/phpgwapi/inc/xml_functions.inc.php
+++ b/phpgwapi/inc/xml_functions.inc.php
@@ -167,7 +167,7 @@
 		);
 		$payload = '<?xml version="1.0"?>' . "\n" . $r->serialize();
 		Header('Content-type: text/xml');
-		Header('Content-length: ' . strlen($payload));
+		Header('Content-length: ' . bytes($payload));
 		print $payload;
 		$GLOBALS['egw']->common->phpgw_exit(False);
 	}
diff --git a/rpc.php b/rpc.php
index 5ada3508c9..52ec9a5181 100644
--- a/rpc.php
+++ b/rpc.php
@@ -117,6 +117,6 @@ $out = $server->getResponse($input, $params);
 
 /* Return the response to the client. */
 header('Content-Type: ' . $server->getResponseContentType());
-header('Content-length: ' . strlen($out));
+header('Content-length: ' . bytes($out));
 header('Accept-Charset: UTF-8');
 echo $out;