diff --git a/README-zh.md b/README-zh.md
index b87f637..60c898f 100644
--- a/README-zh.md
+++ b/README-zh.md
@@ -119,7 +119,7 @@ for i = 1, 10 do
 	logger:fatal("This is a fatal message.")
 end
 
-local pp = require("pp")
+local pp = require("pp") -- https://github.com/luapower/pp
 pp(logger:find("error"))
 
 ```
diff --git a/README.md b/README.md
index 4f1cb50..de2dd6f 100644
--- a/README.md
+++ b/README.md
@@ -115,7 +115,7 @@ for i = 1, 10 do
 	logger:fatal("This is a fatal message.")
 end
 
-local pp = require("pp")
+local pp = require("pp") -- https://github.com/luapower/pp
 pp(logger:find("error"))
 
 ```