diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 206e91ed14..58c15d8d8c 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -252,6 +252,8 @@ async def send_transaction(
 
         path = _create_v1_path("/send/%s", transaction.transaction_id)
 
+        headers: Dict[bytes, List[bytes]] = {b"Accept": [b"application/json"]}
+
         return await self.client.put_json(
             transaction.destination,
             path=path,
@@ -262,6 +264,7 @@ async def send_transaction(
             # Sending a transaction should always succeed, if it doesn't
             # then something is wrong and we should backoff.
             backoff_on_all_error_codes=True,
+            headers=headers,
         )
 
     async def make_query(
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index f6d2536957..2136f2915a 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -532,6 +532,7 @@ async def _send_request_with_optional_trailing_slash(
     async def _send_request(
         self,
         request: MatrixFederationRequest,
+        *,
         retry_on_dns_fail: bool = True,
         timeout: Optional[int] = None,
         long_retries: bool = False,
@@ -539,6 +540,7 @@ async def _send_request(
         backoff_on_404: bool = False,
         backoff_on_all_error_codes: bool = False,
         follow_redirects: bool = False,
+        headers: Optional[Dict[bytes, List[bytes]]] = None,
     ) -> IResponse:
         """
         Sends a request to the given server.
@@ -584,6 +586,9 @@ async def _send_request(
             follow_redirects: True to follow the Location header of 307/308 redirect
                 responses. This does not recurse.
 
+            headers: Additional Headers to pass to the request. Authorization,
+                Content-type, User-Agent and Host will be overridden below
+
         Returns:
             Resolves with the HTTP response object on success.
 
@@ -646,6 +651,8 @@ async def _send_request(
 
         # Inject the span into the headers
         headers_dict: Dict[bytes, List[bytes]] = {}
+        if headers:
+            headers_dict.update(headers)
         opentracing.inject_header_dict(headers_dict, request.destination)
 
         headers_dict[b"User-Agent"] = [self.version_string_bytes]
@@ -754,14 +761,15 @@ async def _send_request(
 
                         return await self._send_request(
                             attr.evolve(request, uri=new_uri, generate_uri=False),
-                            retry_on_dns_fail,
-                            timeout,
-                            long_retries,
-                            ignore_backoff,
-                            backoff_on_404,
-                            backoff_on_all_error_codes,
+                            retry_on_dns_fail=retry_on_dns_fail,
+                            timeout=timeout,
+                            long_retries=long_retries,
+                            ignore_backoff=ignore_backoff,
+                            backoff_on_404=backoff_on_404,
+                            backoff_on_all_error_codes=backoff_on_all_error_codes,
                             # Do not continue following redirects.
                             follow_redirects=False,
+                            headers=headers,
                         )
                     else:
                         logger.info(
@@ -942,6 +950,7 @@ async def put_json(
         try_trailing_slash_on_400: bool = False,
         parser: Literal[None] = None,
         backoff_on_all_error_codes: bool = False,
+        headers: Optional[Dict[bytes, List[bytes]]] = None,
     ) -> JsonDict: ...
 
     @overload
@@ -959,6 +968,7 @@ async def put_json(
         try_trailing_slash_on_400: bool = False,
         parser: Optional[ByteParser[T]] = None,
         backoff_on_all_error_codes: bool = False,
+        headers: Optional[Dict[bytes, List[bytes]]] = None,
     ) -> T: ...
 
     async def put_json(
@@ -975,6 +985,7 @@ async def put_json(
         try_trailing_slash_on_400: bool = False,
         parser: Optional[ByteParser[T]] = None,
         backoff_on_all_error_codes: bool = False,
+        headers: Optional[Dict[bytes, List[bytes]]] = None,
     ) -> Union[JsonDict, T]:
         """Sends the specified json data using PUT
 
@@ -1012,6 +1023,9 @@ async def put_json(
                 parsing as JSON.
             backoff_on_all_error_codes: Back off if we get any error response
 
+            headers: Additional Headers to pass to the request. Authorization,
+                Content-type, User-Agent and Host will be overridden below
+
         Returns:
             Succeeds when we get a 2xx HTTP response. The
             result will be the decoded JSON body.
@@ -1045,6 +1059,7 @@ async def put_json(
             long_retries=long_retries,
             timeout=timeout,
             backoff_on_all_error_codes=backoff_on_all_error_codes,
+            headers=headers,
         )
 
         if timeout is not None: