diff --git a/scripts/network.gd b/scripts/network.gd
index 0b4c58a..53e152f 100644
--- a/scripts/network.gd
+++ b/scripts/network.gd
@@ -78,7 +78,7 @@ class SocketSerial extends SerialPort:
             fcs = (fcs >> 1) ^ P_DIV if fcs & 1 else fcs >> 1
         return (~fcs) & 0xffff
 
-    func try_open(parsing_proc: Callable):
+    func try_open(parsing_proc: Callable) -> Error:
         if is_open():
             return Error.OK
         var rc: = open(port)