diff --git a/gramps/plugins/lib/libgedcom.py b/gramps/plugins/lib/libgedcom.py
index 6c7719775..50e73d420 100644
--- a/gramps/plugins/lib/libgedcom.py
+++ b/gramps/plugins/lib/libgedcom.py
@@ -1238,7 +1238,7 @@ class BaseReader(object):
         self.ifile.seek(0)
 
     def readline(self):
-        raise NotImplemented
+        raise NotImplementedError()
 
     def report_error(self, problem, line):
         line = line.rstrip('\n\r')