diff --git a/adb/common.py b/adb/common.py
index 0c78728..bc59352 100644
--- a/adb/common.py
+++ b/adb/common.py
@@ -304,6 +304,7 @@ def __init__(self, serial, timeout_ms=None):
 
         if ':' in serial:
             self.host, self.port = serial.split(':')
+            self.port = int(self.port)
         else:
             self.host = serial
             self.port = 5555