diff --git a/Hologram/Network/Modem/Modem.py b/Hologram/Network/Modem/Modem.py
index 45f0de7..1077388 100644
--- a/Hologram/Network/Modem/Modem.py
+++ b/Hologram/Network/Modem/Modem.py
@@ -217,6 +217,8 @@ def __detect_all_serial_ports(self, stop_on_first=False, include_all_ports=True)
                         break
                 except Exception as e:
                     self.logger.warning(f"Error attempting to connect to serial port: {e}")
+
+                self.closeSerialPort()
             if stop_on_first and device_names:
                 break
         return device_names
@@ -228,6 +230,7 @@ def detect_usable_serial_port(self, stop_on_first=True):
     def initialize_serial_interface(self):
         self.openSerialPort()
         self.init_serial_commands()
+        self.closeSerialPort()
 
     def init_serial_commands(self):
         self.command("E0") #echo off