diff --git a/CHANGELOG.md b/CHANGELOG.md
index 30431e2..6bb487d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Change Log
 
+## 1.4.0 - 2024-09-01
+
+- No longer automatically add a `Content-Length` header for each part in MultipartStreamBuilder class to comply with RFC 7578 section 4.8.
+
 ## 1.3.1 - 2024-06-10
 
 - Added missing mimetype for `.webp` images.
diff --git a/src/MultipartStreamBuilder.php b/src/MultipartStreamBuilder.php
index a3bcd7b..ca54c05 100644
--- a/src/MultipartStreamBuilder.php
+++ b/src/MultipartStreamBuilder.php
@@ -95,9 +95,9 @@ public function addData($resource, array $headers = [])
      * @param string|resource|StreamInterface $resource
      * @param array                           $options  {
      *
-     *     @var array $headers additional headers ['header-name' => 'header-value']
-     *     @var string $filename
-     * }
+     * @var array  $headers additional headers ['header-name' => 'header-value']
+     * @var string $filename
+     *             }
      *
      * @return MultipartStreamBuilder
      */
@@ -185,13 +185,6 @@ private function prepareHeaders($name, StreamInterface $stream, $filename, array
             }
         }
 
-        // Set a default content-length header if one was not provided
-        if (!$this->hasHeader($headers, 'content-length')) {
-            if ($length = $stream->getSize()) {
-                $headers['Content-Length'] = (string) $length;
-            }
-        }
-
         // Set a default Content-Type if one was not provided
         if (!$this->hasHeader($headers, 'content-type') && $hasFilename) {
             if ($type = $this->getMimetypeHelper()->getMimetypeFromFilename($filename)) {
diff --git a/tests/FunctionTest.php b/tests/FunctionTest.php
index 64b31a6..52e84ea 100644
--- a/tests/FunctionTest.php
+++ b/tests/FunctionTest.php
@@ -88,13 +88,16 @@ public function testHeaders()
         $this->assertTrue(false === strpos($multipartStream, 'Content-Disposition:'));
     }
 
-    public function testContentLength()
+    /**
+     * Comply with RFC 7578 section 4.8
+     */
+    public function testShouldNotContainContentLength()
     {
         $builder = new MultipartStreamBuilder();
         $builder->addResource('foobar', 'stream contents');
 
         $multipartStream = (string) $builder->build();
-        $this->assertTrue(false !== strpos($multipartStream, 'Content-Length: 15'));
+        $this->assertTrue(false === strpos($multipartStream, 'Content-Length:'));
     }
 
     public function testFormName()