diff --git a/src/Message/Part/MimePart.php b/src/Message/Part/MimePart.php
index 28968abe..ecc0c872 100644
--- a/src/Message/Part/MimePart.php
+++ b/src/Message/Part/MimePart.php
@@ -30,7 +30,7 @@ public function isMultiPart()
     {
         // casting to bool, preg_match returns 1 for true
         return (bool) (preg_match(
-            '~multipart/\w+~i',
+            '~multipart/.*~i',
             $this->getContentType()
         ));
     }
diff --git a/src/Message/Part/PartBuilder.php b/src/Message/Part/PartBuilder.php
index 2ee6798b..f8a82265 100644
--- a/src/Message/Part/PartBuilder.php
+++ b/src/Message/Part/PartBuilder.php
@@ -242,7 +242,7 @@ public function isMultiPart()
         if ($contentType !== null) {
             // casting to bool, preg_match returns 1 for true
             return (bool) (preg_match(
-                '~multipart/\w+~i',
+                '~multipart/.*~i',
                 $contentType->getValue()
             ));
         }
diff --git a/tests/MailMimeParser/IntegrationTests/EmailFunctionalTest.php b/tests/MailMimeParser/IntegrationTests/EmailFunctionalTest.php
index 92b516a0..b1d5d815 100644
--- a/tests/MailMimeParser/IntegrationTests/EmailFunctionalTest.php
+++ b/tests/MailMimeParser/IntegrationTests/EmailFunctionalTest.php
@@ -1728,6 +1728,31 @@ public function testParseEmailGitHub_102_02()
         ]);
     }
 
+    public function testParseEmailGitHub_115()
+    {
+        $this->runEmailTest('github-115', [
+            'From' => [
+                'name' => 'Doug Sauder',
+                'email' => 'doug@example.com'
+            ],
+            'To' => [
+                'name' => 'Heinz Müller',
+                'email' => 'mueller@example.com'
+            ],
+            'Subject' => 'Test message from Microsoft Outlook 00',
+            'text' => 'hareandtortoise.txt',
+            'attachments' => 3,
+            'parts' => [
+                'multipart/*' => [
+                    'text/plain',
+                    'image/png',
+                    'image/png',
+                    'image/png'
+                ]
+            ],
+        ]);
+    }
+
     public function testRewriteEmailContentm0001()
     {
         $handle = fopen($this->messageDir . '/m0001.txt', 'r');
diff --git a/tests/_data/emails/github-115.txt b/tests/_data/emails/github-115.txt
new file mode 100644
index 00000000..3dc1b4bd
--- /dev/null
+++ b/tests/_data/emails/github-115.txt
@@ -0,0 +1,135 @@
+From: "Doug Sauder" <doug@example.com>
+To: =?iso-8859-1?Q?Heinz_M=FCller?= <mueller@example.com>
+Subject: Test message from Microsoft Outlook 00
+Date: Wed, 17 May 2000 19:32:47 -0400
+Message-ID: <NDBBIAKOPKHFGPLCODIGGEKECHAA.doug@example.com>
+MIME-Version: 1.0
+Content-Type: multipart/*;
+    boundary="----=_NextPart_000_0002_01BFC036.AE309650"
+X-Priority: 3 (Normal)
+X-MSMail-Priority: Normal
+X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)
+Importance: Normal
+X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300
+
+This is a multi-part message in MIME format.
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: text/plain;
+    charset="iso-8859-1"
+Content-Transfer-Encoding: quoted-printable
+
+
+The Hare and the Tortoise=20
+=20
+A HARE one day ridiculed the short feet and slow pace of the Tortoise, =
+who replied, laughing:  "Though you be swift as the wind, I will beat =
+you in a race."  The Hare, believing her assertion to be simply =
+impossible, assented to the proposal; and they agreed that the Fox =
+should choose the course and fix the goal.  On the day appointed for the =
+race the two started together.  The Tortoise never for a moment stopped, =
+but went on with a slow but steady pace straight to the end of the =
+course.  The Hare, lying down by the wayside, fell fast asleep.  At last =
+waking up, and moving as fast as he could, he saw the Tortoise had =
+reached the goal, and was comfortably dozing after her fatigue. =20
+=20
+Slow but steady wins the race. =20
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png;
+    name="blueball.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+    filename="blueball.png"
+
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+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
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+O7wAAAAASUVORK5CYII=
+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png;
+    name="greenball.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+    filename="greenball.png"
+
+iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAMAAAC6CgRnAAADAFBMVEX///8AAAAAEAAAGAAAIQAA
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+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
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+
+------=_NextPart_000_0002_01BFC036.AE309650
+Content-Type: image/png;
+    name="redball.png"
+Content-Transfer-Encoding: base64
+Content-Disposition: attachment;
+    filename="redball.png"
+
+iVBORw0KGgoAAAANSUhEUgAAABsAAAAbCAMAAAC6CgRnAAADAFBMVEX///8AAAABAAALAAAVAAAa
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+
+------=_NextPart_000_0002_01BFC036.AE309650--