diff --git a/log_tsl2591.py b/log_tsl2591.py
index 9362f40..975e262 100644
--- a/log_tsl2591.py
+++ b/log_tsl2591.py
@@ -24,6 +24,7 @@ if "tsl2591" in log_conf:
     if log_conf['tsl2591']['enable'] == 0:
       btls=False
   if btls:
+# https://github.com/maxlklaxl/python-tsl2591
     import tsl2591
     tsl_port=1
     if "port" in log_conf['tsl2591']: