diff --git a/src/Header/AbstractAccept.php b/src/Header/AbstractAccept.php
index 7a8c379ee4..13b9c2cf78 100644
--- a/src/Header/AbstractAccept.php
+++ b/src/Header/AbstractAccept.php
@@ -168,6 +168,10 @@ protected function getParametersFromFieldValuePart($fieldValuePart)
             }
 
             foreach ($paramsStrings as $param) {
+                if (strpos($param, '=') === false) {
+                    continue;
+                }
+
                 $explode = explode('=', $param, 2);
 
                 $value = trim($explode[1]);
diff --git a/test/Header/AcceptLanguageTest.php b/test/Header/AcceptLanguageTest.php
index bc7d4eb6b2..71b71898ea 100644
--- a/test/Header/AcceptLanguageTest.php
+++ b/test/Header/AcceptLanguageTest.php
@@ -32,6 +32,12 @@ public function testAcceptLanguageGetFieldValueReturnsProperValue()
         $this->assertEquals('xxx', $acceptLanguageHeader->getFieldValue());
     }
 
+    public function testAcceptLanguageGetFieldValueReturnsProperNonWellFormattedHeaderValue()
+    {
+        $acceptLanguageHeader = AcceptLanguage::fromString('Accept-Language: en-US;en');
+        $this->assertEquals('en-US', $acceptLanguageHeader->getFieldValue());
+    }
+
     public function testAcceptLanguageToStringReturnsHeaderFormattedString()
     {
         $acceptLanguageHeader = new AcceptLanguage();