diff --git a/coreapi/chat.c b/coreapi/chat.c
index 0c89485f3..f9322bdd0 100644
--- a/coreapi/chat.c
+++ b/coreapi/chat.c
@@ -36,8 +36,6 @@
 
 
 static void _linphone_chat_room_send_message(LinphoneChatRoom *cr, LinphoneChatMessage* msg);
-#define MULTIPART_BOUNDARY "---------------------------14737809831466499882746641449"
-const char *multipart_boundary=MULTIPART_BOUNDARY;
 
 static void process_io_error_upload(void *data, const belle_sip_io_error_event_t *event){
 	LinphoneChatMessage* msg=(LinphoneChatMessage *)data;
@@ -128,7 +126,6 @@ static void linphone_chat_message_process_response_from_post_file(void *data, co
 			belle_http_request_t *req;
 			belle_sip_multipart_body_handler_t *bh;
 			char* ua;
-			char *content_type;
 			char *first_part_header;
 			belle_sip_user_body_handler_t *first_part_bh;
 
@@ -144,19 +141,14 @@ static void linphone_chat_message_process_response_from_post_file(void *data, co
 			/* insert it in a multipart body handler which will manage the boundaries of multipart message */
 			bh=belle_sip_multipart_body_handler_new(linphone_chat_message_file_transfer_on_progress, msg,  (belle_sip_body_handler_t *)first_part_bh);
 
+			/* create the http request: do not include the message header at this point, it is done by bellesip when setting the multipart body handler in the message */
 			ua = ms_strdup_printf("%s/%s", linphone_core_get_user_agent_name(), linphone_core_get_user_agent_version());
-
-			content_type=belle_sip_strdup_printf("multipart/form-data; boundary=%s",multipart_boundary);
-
 			uri=belle_generic_uri_parse(linphone_core_get_file_transfer_server(msg->chat_room->lc));
-
 			req=belle_http_request_create("POST",
 										  uri,
 										  belle_sip_header_create("User-Agent",ua),
-										  belle_sip_header_create("Content-type",content_type),
 										  NULL);
 			ms_free(ua);
-			belle_sip_free(content_type);
 			belle_sip_message_set_body_handler(BELLE_SIP_MESSAGE(req),BELLE_SIP_BODY_HANDLER(bh));
 			cbs.process_response=linphone_chat_message_process_response_from_post_file;
 			cbs.process_io_error=process_io_error_upload;
diff --git a/coreapi/linphonecore.c b/coreapi/linphonecore.c
index 827553dd1..5f794718f 100644
--- a/coreapi/linphonecore.c
+++ b/coreapi/linphonecore.c
@@ -276,8 +276,6 @@ static void process_auth_requested_upload_log_collection(void *data, belle_sip_a
 	delete_log_collection_upload_file();
 }
 
-extern const char *multipart_boundary;
-
 /**
  * Callback called when posting a log collection file to server (following rcs5.1 recommendation)
  *
@@ -341,7 +339,6 @@ static void process_response_from_post_file_log_collection(void *data, const bel
 			belle_http_request_t *req;
 			belle_sip_multipart_body_handler_t *bh;
 			char* ua;
-			char *content_type;
 			char *first_part_header;
 			belle_sip_user_body_handler_t *first_part_bh;
 
@@ -359,11 +356,9 @@ static void process_response_from_post_file_log_collection(void *data, const bel
 			/* Insert it in a multipart body handler which will manage the boundaries of multipart message */
 			bh = belle_sip_multipart_body_handler_new(log_collection_upload_on_progress, core, (belle_sip_body_handler_t *)first_part_bh);
 			ua = ms_strdup_printf("%s/%s", linphone_core_get_user_agent_name(), linphone_core_get_user_agent_version());
-			content_type = belle_sip_strdup_printf("multipart/form-data; boundary=%s", multipart_boundary);
 			uri = belle_generic_uri_parse(linphone_core_get_log_collection_upload_server_url(core));
-			req = belle_http_request_create("POST", uri, belle_sip_header_create("User-Agent", ua), belle_sip_header_create("Content-type", content_type), NULL);
+			req = belle_http_request_create("POST", uri, belle_sip_header_create("User-Agent", ua), NULL);
 			ms_free(ua);
-			belle_sip_free(content_type);
 			belle_sip_message_set_body_handler(BELLE_SIP_MESSAGE(req), BELLE_SIP_BODY_HANDLER(bh));
 			cbs.process_response = process_response_from_post_file_log_collection;
 			cbs.process_io_error = process_io_error_upload_log_collection;