diff --git a/src/aiooss2/http.py b/src/aiooss2/http.py
index c128cfc..8afc447 100644
--- a/src/aiooss2/http.py
+++ b/src/aiooss2/http.py
@@ -41,7 +41,8 @@ def __init__(  # pylint: disable=too-many-arguments
         else:
             self.headers = headers
 
-        self.headers["Content-Type"] = "application/octet-stream"
+        if "Content-Type" not in self.headers:
+            self.headers["Content-Type"] = "application/octet-stream"
         if "User-Agent" not in self.headers:
             if app_name:
                 self.headers["User-Agent"] = USER_AGENT + "/" + app_name