diff --git a/BinaryFileResponse.php b/BinaryFileResponse.php
index 6eddd6c28..2c4d831bb 100644
--- a/BinaryFileResponse.php
+++ b/BinaryFileResponse.php
@@ -189,7 +189,12 @@ public function prepare(Request $request): static
         }
 
         if (!$this->headers->has('Content-Type')) {
-            $this->headers->set('Content-Type', $this->file->getMimeType() ?: 'application/octet-stream');
+            $mimeType = null;
+            if (!$this->tempFileObject) {
+                $mimeType = $this->file->getMimeType();
+            }
+
+            $this->headers->set('Content-Type', $mimeType ?: 'application/octet-stream');
         }
 
         parent::prepare($request);
diff --git a/Tests/BinaryFileResponseTest.php b/Tests/BinaryFileResponseTest.php
index 2951cdb51..1263fa392 100644
--- a/Tests/BinaryFileResponseTest.php
+++ b/Tests/BinaryFileResponseTest.php
@@ -468,4 +468,15 @@ public function testSetChunkSizeTooSmall()
 
         $response->setChunkSize(0);
     }
+
+    public function testCreateFromTemporaryFileWithoutMimeType()
+    {
+        $file = new \SplTempFileObject();
+        $file->fwrite('foo,bar');
+
+        $response = new BinaryFileResponse($file);
+        $response->prepare(new Request());
+
+        $this->assertSame('application/octet-stream', $response->headers->get('Content-Type'));
+    }
 }