diff --git a/README.md b/README.md
index 7f601e6..f01ef54 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@ My solutions to the Advent of Code 2023 programming challenges.
 
 Thanks to Eric Wastl for creating this enjoyable event.
 
+Requires `lib.py` from [aocpy](https://git.felixm.de/felixm/aocpy) repository.
+
 
 # Times