diff --git a/NEWS b/NEWS
index b8f9d35f..65f4936a 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ What's new in psycopg 2.7.4
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 - Fixed Solaris 10 support (:ticket:`#532`).
+- Fixed `MinTimeLoggingCursor` on Python 3 (:ticket:`#609`).
 - Fixed parsing of array of points as floats (:ticket:`#613`).
 
 
diff --git a/lib/extras.py b/lib/extras.py
index 8abb14fc..bfac2df3 100644
--- a/lib/extras.py
+++ b/lib/extras.py
@@ -455,6 +455,8 @@ class MinTimeLoggingConnection(LoggingConnection):
     def filter(self, msg, curs):
         t = (_time.time() - curs.timestamp) * 1000
         if t > self._mintime:
+            if _sys.version_info[0] >= 3 and isinstance(msg, bytes):
+                msg = msg.decode(_ext.encodings[self.encoding], 'replace')
             return msg + _os.linesep + "  (execution time: %d ms)" % t
 
     def cursor(self, *args, **kwargs):