diff --git a/src/MultipartStream.php b/src/MultipartStream.php
index 43d718f6..337d7d91 100644
--- a/src/MultipartStream.php
+++ b/src/MultipartStream.php
@@ -131,14 +131,6 @@ private function createElement(string $name, StreamInterface $stream, ?string $f
                 : "form-data; name=\"{$name}\"";
         }
 
-        // Set a default content-length header if one was no provided
-        $length = self::getHeader($headers, 'content-length');
-        if (!$length) {
-            if ($length = $stream->getSize()) {
-                $headers['Content-Length'] = (string) $length;
-            }
-        }
-
         // Set a default Content-Type if one was not supplied
         $type = self::getHeader($headers, 'content-type');
         if (!$type && ($filename === '0' || $filename)) {
diff --git a/tests/MultipartStreamTest.php b/tests/MultipartStreamTest.php
index ed778e0c..bf2652aa 100644
--- a/tests/MultipartStreamTest.php
+++ b/tests/MultipartStreamTest.php
@@ -64,12 +64,10 @@ public function testSerializesFields(): void
         $expected = \implode('', [
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"foo\"\r\n",
-            "Content-Length: 3\r\n",
             "\r\n",
             "bar\r\n",
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"baz\"\r\n",
-            "Content-Length: 3\r\n",
             "\r\n",
             "bam\r\n",
             "--boundary--\r\n",
@@ -102,7 +100,6 @@ public function testSerializesNonStringFields(): void
         $expected = \implode('', [
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"int\"\r\n",
-            "Content-Length: 1\r\n",
             "\r\n",
             "1\r\n",
             "--boundary\r\n",
@@ -112,12 +109,10 @@ public function testSerializesNonStringFields(): void
             '--boundary',
             "\r\n",
             "Content-Disposition: form-data; name=\"bool2\"\r\n",
-            "Content-Length: 1\r\n",
             "\r\n",
             "1\r\n",
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"float\"\r\n",
-            "Content-Length: 3\r\n",
             "\r\n",
             "1.1\r\n",
             "--boundary--\r\n",
@@ -165,19 +160,16 @@ public function testSerializesFiles(): void
         $expected = \implode('', [
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"foo\"; filename=\"bar.txt\"\r\n",
-            "Content-Length: 3\r\n",
             "Content-Type: text/plain\r\n",
             "\r\n",
             "foo\r\n",
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"qux\"; filename=\"baz.jpg\"\r\n",
-            "Content-Length: 3\r\n",
             "Content-Type: image/jpeg\r\n",
             "\r\n",
             "baz\r\n",
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"qux\"; filename=\"bar.unknown\"\r\n",
-            "Content-Length: 3\r\n",
             "Content-Type: application/octet-stream\r\n",
             "\r\n",
             "bar\r\n",
@@ -208,7 +200,6 @@ public function testSerializesFilesWithMixedNewlines(): void
         $expected = \implode('', [
             "--boundary\r\n",
             "Content-Disposition: form-data; name=\"newlines\"; filename=\"newlines.txt\"\r\n",
-            "Content-Length: {$contentLength}\r\n",
             "Content-Type: text/plain\r\n",
             "\r\n",
             "{$content}\r\n",
@@ -243,7 +234,6 @@ public function testSerializesFilesWithCustomHeaders(): void
             "--boundary\r\n",
             "x-foo: bar\r\n",
             "content-disposition: custom\r\n",
-            "Content-Length: 3\r\n",
             "Content-Type: text/plain\r\n",
             "\r\n",
             "foo\r\n",
@@ -287,14 +277,12 @@ public function testSerializesFilesWithCustomHeadersAndMultipleValues(): void
             "--boundary\r\n",
             "x-foo: bar\r\n",
             "content-disposition: custom\r\n",
-            "Content-Length: 3\r\n",
             "Content-Type: text/plain\r\n",
             "\r\n",
             "foo\r\n",
             "--boundary\r\n",
             "cOntenT-Type: custom\r\n",
             "Content-Disposition: form-data; name=\"foo\"; filename=\"baz.jpg\"\r\n",
-            "Content-Length: 3\r\n",
             "\r\n",
             "baz\r\n",
             "--boundary--\r\n",