diff --git a/README.md b/README.md
index 391c648..a23494f 100644
--- a/README.md
+++ b/README.md
@@ -164,3 +164,11 @@ It uses the default Twain/Shakespeare model for both, and for classification it
 uses [Mark Antony's "Friends, Romans, countrymen"
 speech](https://en.wikipedia.org/wiki/Friends,_Romans,_countrymen,_lend_me_your_ears)
 from Shakespeare's *Julius Caesar*.
+
+## Please only use GPTC in copylefted (e.g. GPL'ed) software
+
+GPTC is licensed under the Lesser General Public License; this does allow use 
+in non-GPL'ed software. However, this license is only used for compatibility
+with [CedarSentinel](https://github.com/fire219/CedarSentinel), released under
+the MIT license. While this request is not legally binding, I would appreciate
+it if GPTC was not used in non-copyleft software.
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