diff --git a/src/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyser.php b/src/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyser.php
index 6aacb33..5ab33fe 100644
--- a/src/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyser.php
+++ b/src/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyser.php
@@ -27,7 +27,7 @@ class MimeBoundaryAnalyser
      */
     public static function isMessageLineBoundary($mimeMessageLine)
     {
-        return strlen($mimeMessageLine) > 0 && $mimeMessageLine[0] === "-";
+        return preg_match('/^--[0-9A-Za-z\s\'\/\+\_\,\-\.\:\=\?]+/', $mimeMessageLine) === 1;
     }
 
     /**
diff --git a/tests/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyserTest.php b/tests/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyserTest.php
index a872a3a..eefe2cf 100644
--- a/tests/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyserTest.php
+++ b/tests/BeSimple/SoapCommon/Mime/Boundary/MimeBoundaryAnalyserTest.php
@@ -67,6 +67,8 @@ class MimeBoundaryAnalyserTest extends PHPUnit_Framework_TestCase
     {
         return [
             ['-- this line is boundary', self::EXPECTED_IS_BOUNDARY],
+            ['--this line is boundary', self::EXPECTED_IS_BOUNDARY],
+            ['--@ this line is not boundary', self::EXPECTED_IS_NOT_BOUNDARY],
             ['-- this line is also a boundary --', self::EXPECTED_IS_BOUNDARY],
             ['mesage line -- is not boundary', self::EXPECTED_IS_NOT_BOUNDARY],
             [' -- mesage line -- is not boundary', self::EXPECTED_IS_NOT_BOUNDARY],