diff --git a/alarmdecoder/util.py b/alarmdecoder/util.py
index 902b21d..2702a13 100644
--- a/alarmdecoder/util.py
+++ b/alarmdecoder/util.py
@@ -97,7 +97,10 @@ def filter_ad2prot_byte(buf):
     """
     Return the byte sent in back if valid visible terminal characters or line terminators.
     """
-    c = buf[0]
+    if sys.version_info > (3,):
+        c = buf[0]
+    else:
+        c = ord(buf)
 
     if (c == 10 or c == 13):
         return buf
diff --git a/test/test_devices.py b/test/test_devices.py
index 17cba61..d418780 100644
--- a/test/test_devices.py
+++ b/test/test_devices.py
@@ -80,8 +80,11 @@ class TestSerialDevice(TestCase):
     def test_read(self):
         self._device.interface = '/dev/ttyS0'
         self._device.open(no_reader_thread=True)
+        side_effect = ["t"]
+        if sys.version_info > (3,):
+            side_effect = ["t".encode('utf-8')]
 
-        with patch.object(self._device._device, 'read', return_value=[1]) as mock:
+        with patch.object(self._device._device, 'read', side_effect=side_effect) as mock:
             with patch('serial.Serial.fileno', return_value=1):
                 with patch.object(select, 'select', return_value=[[1], [], []]):
                     ret = self._device.read()