diff --git a/plugin/cobol.py b/plugin/cobol.py
index 97b66101cb9c5e76841ee9cd15b10885d1f77000..20c1031deed1ea127af36754927d2d3c9cbcb8f3 100755
--- a/plugin/cobol.py
+++ b/plugin/cobol.py
@@ -11,6 +11,7 @@ from __future__ import print_function
 COBOL utilities.
 """
 
+# See :help python-vim for how this module works.
 import vim
 import math