diff --git a/CHANGES.rst b/CHANGES.rst
index abcf752..85633f0 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -656,6 +656,8 @@
 Bugfixes:
 
 - [#137] Exception while cancel in miniterm (python3)
+- [#143] Class Serial in protocol_loop.py references variable before assigning
+  to it
 
 Bugfixes (posix):
 
diff --git a/serial/urlhandler/protocol_loop.py b/serial/urlhandler/protocol_loop.py
index 819da77..a387208 100644
--- a/serial/urlhandler/protocol_loop.py
+++ b/serial/urlhandler/protocol_loop.py
@@ -43,10 +43,10 @@
                  9600, 19200, 38400, 57600, 115200)
 
     def __init__(self, *args, **kwargs):
-        super(Serial, self).__init__(*args, **kwargs)
         self.buffer_size = 4096
         self.queue = None
         self.logger = None
+        super(Serial, self).__init__(*args, **kwargs)
 
     def open(self):
         """\