diff --git a/src/Symfony/Component/HttpClient/HttplugClient.php b/src/Symfony/Component/HttpClient/HttplugClient.php
index 8e1dc1c4cb9e3..1d7632425cfc1 100644
--- a/src/Symfony/Component/HttpClient/HttplugClient.php
+++ b/src/Symfony/Component/HttpClient/HttplugClient.php
@@ -234,13 +234,13 @@ private function sendPsr7Request(RequestInterface $request, ?bool $buffer = null
             }
 
             $headers = $request->getHeaders();
-            if (!$request->hasHeader('content-length') && 0 <= $size = $body->getSize() ?? -1) {
+            if (!$request->hasHeader('content-length') && 0 < $size = $body->getSize() ?? -1) {
                 $headers['Content-Length'] = [$size];
             }
 
             $options = [
                 'headers' => $headers,
-                'body' => static fn (int $size) => $body->read($size),
+                'body' => 0 === $size ? '' : static fn (int $size) => $body->read($size),
                 'buffer' => $buffer,
             ];
 
diff --git a/src/Symfony/Component/HttpClient/Psr18Client.php b/src/Symfony/Component/HttpClient/Psr18Client.php
index a2a19236e8f67..7b59e8bd0f133 100644
--- a/src/Symfony/Component/HttpClient/Psr18Client.php
+++ b/src/Symfony/Component/HttpClient/Psr18Client.php
@@ -98,13 +98,13 @@ public function sendRequest(RequestInterface $request): ResponseInterface
             }
 
             $headers = $request->getHeaders();
-            if (!$request->hasHeader('content-length') && 0 <= $size = $body->getSize() ?? -1) {
+            if (!$request->hasHeader('content-length') && 0 < $size = $body->getSize() ?? -1) {
                 $headers['Content-Length'] = [$size];
             }
 
             $options = [
                 'headers' => $headers,
-                'body' => static fn (int $size) => $body->read($size),
+                'body' => 0 === $size ? '' : static fn (int $size) => $body->read($size),
             ];
 
             if ('1.0' === $request->getProtocolVersion()) {