diff --git a/coreapi/chat.c b/coreapi/chat.c
index 1f1afbb1f..b36196468 100644
--- a/coreapi/chat.c
+++ b/coreapi/chat.c
@@ -37,16 +37,8 @@
 
 static void _linphone_chat_room_send_message(LinphoneChatRoom *cr, LinphoneChatMessage* msg);
 #define MULTIPART_BOUNDARY "---------------------------14737809831466499882746641449"
-#define FILEPART_HEADER_1 "Content-Disposition: form-data; name=\"File\"; filename=\""
-#define FILEPART_HEADER_2 "\"\r\n" \
-			"Content-Type: "
-#define FILEPART_HEADER_3 "\r\n\r\n"
 const char *multipart_boundary=MULTIPART_BOUNDARY;
 
-static size_t linphone_chat_message_compute_filepart_header_size(const char *filename, const char *content_type) {
-	return strlen(FILEPART_HEADER_1)+strlen(filename)+strlen(FILEPART_HEADER_2)+strlen(content_type)+strlen(FILEPART_HEADER_3);
-}
-
 static void process_io_error_upload(void *data, const belle_sip_io_error_event_t *event){
 	LinphoneChatMessage* msg=(LinphoneChatMessage *)data;
 	ms_error("I/O Error during file upload to %s - msg [%p] chat room[%p]", msg->chat_room->lc->file_transfer_server, msg, msg->chat_room);
@@ -107,28 +99,12 @@ static int linphone_chat_message_file_transfer_on_send_body(belle_sip_user_body_
 	LinphoneCore *lc = chatMsg->chat_room->lc;
 	char *buf = (char *)buffer;
 
-	char *content_type=belle_sip_strdup_printf("%s/%s", chatMsg->file_transfer_information->type, chatMsg->file_transfer_information->subtype);
-	size_t end_of_file=linphone_chat_message_compute_filepart_header_size(chatMsg->file_transfer_information->name, content_type)+chatMsg->file_transfer_information->size;
-
-	if (offset==0){
-		int partlen=linphone_chat_message_compute_filepart_header_size(chatMsg->file_transfer_information->name, content_type);
-		memcpy(buf,FILEPART_HEADER_1,strlen(FILEPART_HEADER_1));
-		buf += strlen(FILEPART_HEADER_1);
-		memcpy(buf,chatMsg->file_transfer_information->name,strlen(chatMsg->file_transfer_information->name));
-		buf += strlen(chatMsg->file_transfer_information->name);
-		memcpy(buf,FILEPART_HEADER_2,strlen(FILEPART_HEADER_2));
-		buf += strlen(FILEPART_HEADER_2);
-		memcpy(buf,content_type,strlen(content_type));
-		buf += strlen(content_type);
-		memcpy(buf,FILEPART_HEADER_3,strlen(FILEPART_HEADER_3));
-
-		*size=partlen;
-	}else if (offset<end_of_file){
+	/* if we've not reach the end of file yet, ask for more data*/
+	if (offset<chatMsg->file_transfer_information->size){
 		/* get data from call back */
 		lc->vtable.file_transfer_send(lc, chatMsg, chatMsg->file_transfer_information, buf, size);
 	}
 
-	belle_sip_free(content_type);
 	return BELLE_SIP_CONTINUE;
 }
 
@@ -152,12 +128,16 @@ static void linphone_chat_message_process_response_from_post_file(void *data, co
 			belle_http_request_listener_t *l;
 			belle_generic_uri_t *uri;
 			belle_http_request_t *req;
+
+			/* temporary storage of the header of the message part header */
 			char *content_type=belle_sip_strdup_printf("%s/%s", msg->file_transfer_information->type, msg->file_transfer_information->subtype);
+			char *first_part_header = belle_sip_strdup_printf("Content-Disposition: form-data; name=\"File\"; filename=\"%s\"\r\nContent-Type: %s\r\n\r\n", msg->file_transfer_information->name, content_type);
 
 			/* create a user body handler to take care of the file */
-			size_t body_size = msg->file_transfer_information->size+linphone_chat_message_compute_filepart_header_size(msg->file_transfer_information->name, content_type);
+			belle_sip_user_body_handler_t *first_part_bh=belle_sip_user_body_handler_new(msg->file_transfer_information->size,NULL,NULL,linphone_chat_message_file_transfer_on_send_body,msg);
+			belle_sip_body_handler_set_header((belle_sip_body_handler_t *)first_part_bh, first_part_header); /* set the header for this part */
+			belle_sip_free(first_part_header);
 
-			belle_sip_user_body_handler_t *first_part_bh=belle_sip_user_body_handler_new(body_size,NULL,NULL,linphone_chat_message_file_transfer_on_send_body,msg);
 			/* insert it in a multipart body handler which will manage the boundaries of multipart message */
 			belle_sip_multipart_body_handler_t *bh=belle_sip_multipart_body_handler_new(linphone_chat_message_file_transfer_on_progress, msg,  (belle_sip_body_handler_t *)first_part_bh);