diff --git a/src/xpra/server/proxy/proxy_instance_process.py b/src/xpra/server/proxy/proxy_instance_process.py
index 92666b44db..e9b1f3ccc1 100644
--- a/src/xpra/server/proxy/proxy_instance_process.py
+++ b/src/xpra/server/proxy/proxy_instance_process.py
@@ -181,6 +181,8 @@ def run(self):
         self.server_protocol.large_packets.append("window-icon")
         self.server_protocol.large_packets.append("keymap-changed")
         self.server_protocol.large_packets.append("server-settings")
+        if self.caps.boolget("file-transfer"):
+            self.server_protocol.large_packets.append("send-file")
         self.server_protocol.set_compression_level(self.session_options.get("compression_level", 0))
         self.server_protocol.enable_default_encoder()
 
@@ -551,14 +553,19 @@ def process_server_packet(self, proto, packet):
         elif packet_type=="hello":
             c = typedict(packet[1])
             maxw, maxh = c.intpair("max_desktop_size", (4096, 4096))
-            proto.max_packet_size = maxw*maxh*4*4
-
             caps = self.filter_server_caps(c)
             #add new encryption caps:
             if self.cipher:
                 padding_options = self.caps.strlistget("cipher.padding.options", [DEFAULT_PADDING])
                 auth_caps = new_cipher_caps(self.client_protocol, self.cipher, self.encryption_key, padding_options)
                 caps.update(auth_caps)
+            #may need to bump packet size:
+            proto.max_packet_size = maxw*maxh*4*4
+            file_transfer = self.caps.boolget("file-transfer") and c.boolget("file-transfer")
+            file_size_limit = max(self.caps.intget("file-size-limit"), c.intget("file-size-limit"))
+            file_max_packet_size = int(file_transfer) * (1024 + file_size_limit*1024*1024)
+            self.client_protocol.max_packet_size = max(self.client_protocol.max_packet_size, file_max_packet_size)
+            self.server_protocol.max_packet_size = max(self.server_protocol.max_packet_size, file_max_packet_size)
             packet = ("hello", caps)
         elif packet_type=="info-response":
             #adds proxy info:
diff --git a/src/xpra/server/server_base.py b/src/xpra/server/server_base.py
index 02797fca24..20c0b54764 100644
--- a/src/xpra/server/server_base.py
+++ b/src/xpra/server/server_base.py
@@ -889,6 +889,7 @@ def get_window_id(wid):
         log("process_hello serversource=%s", ss)
         try:
             ss.parse_hello(c)
+            proto.max_packet_size = max(proto.max_packet_size, int(ss.file_transfer) * (1024 + ss.file_size_limit*1024*1024))
         except:
             #close it already
             ss.close()
@@ -898,6 +899,12 @@ def get_window_id(wid):
         send_ui = ui_client and not is_request
         self.idle_add(self.parse_hello_ui, ss, c, auth_caps, send_ui, share_count)
 
+    def accept_client(self, proto, c):
+        ServerCore.accept_client(self, proto, c)
+        #may need to bump file size limit for file transfers:
+        proto.max_packet_size = max(proto.max_packet_size, int(self.file_transfer) * (1024 + self.file_size_limit*1024*1024))
+
+
     def get_server_source_class(self):
         from xpra.server.source import ServerSource
         return ServerSource