diff --git a/src/escpos/printer/network.py b/src/escpos/printer/network.py
index 360fcff..16323e2 100644
--- a/src/escpos/printer/network.py
+++ b/src/escpos/printer/network.py
@@ -118,7 +118,7 @@ class Network(Escpos):
         """Read data from the TCP socket."""
         return self.device.recv(16)
 
-    def close(self):
+    def close(self) -> None:
         """Close TCP connection."""
         if not self._device:
             return