diff --git a/pyof/v0x01/controller2switch/packet_out.py b/pyof/v0x01/controller2switch/packet_out.py
index 5996d4712..ad906e331 100644
--- a/pyof/v0x01/controller2switch/packet_out.py
+++ b/pyof/v0x01/controller2switch/packet_out.py
@@ -112,13 +112,20 @@ def _update_actions_len(self):
             self.actions_len = ListOfActions(self.actions).get_size()
 
     def _validate_in_port(self):
-        port = self.in_port
-        valid = True
-        if isinstance(port, Port):
-            if port not in _VIRT_IN_PORTS:
-                valid = False
-        elif isinstance(port, int) and (port < 1 or port >=
-                                        Port.OFPP_MAX.value):
-            valid = False
-        if not valid:
-            raise ValidationError('{} is not a valid input port.'.format(port))
+        """Validate in_port attribute.
+
+        A valid port is either:
+
+            * Greater than 0 and less than or equals to Port.OFPP_MAX
+            * One of the valid virtual ports: Port.OFPP_LOCAL,
+              Port.OFPP_CONTROLLER or Port.OFPP_NONE
+
+        Raises:
+            ValidationError: If in_port is an invalid port.
+
+        """
+        is_valid_range = self.in_port > 0 and self.in_port <= Port.OFPP_MAX
+        is_valid_virtual_in_ports = self.in_port in _VIRT_IN_PORTS
+
+        if (is_valid_range or is_valid_virtual_in_ports) is False:
+            raise ValidationError(f'{self.in_port} is not a valid input port.')
diff --git a/tests/v0x01/test_controller2switch/test_packet_out.py b/tests/v0x01/test_controller2switch/test_packet_out.py
index 00ea79783..7a277ee81 100644
--- a/tests/v0x01/test_controller2switch/test_packet_out.py
+++ b/tests/v0x01/test_controller2switch/test_packet_out.py
@@ -45,14 +45,14 @@ def test_invalid_virtual_in_ports(self):
 
     def test_valid_physical_in_ports(self):
         """Physical port limits from 1.0.0 spec."""
-        max_valid = int(Port.OFPP_MAX.value) - 1
+        max_valid = int(Port.OFPP_MAX.value)
         for in_port in (1, max_valid):
             self.message.in_port = in_port
             self.assertTrue(self.message.is_valid())
 
     def test_invalid_physical_in_port(self):
         """Physical port limits from 1.0.0 spec."""
-        max_valid = int(Port.OFPP_MAX.value) - 1
+        max_valid = int(Port.OFPP_MAX.value)
         for in_port in (-1, 0, max_valid + 1, max_valid + 2):
             self.message.in_port = in_port
             self.assertFalse(self.message.is_valid())