diff --git a/packages/zenn-cli/src/client/global.css b/packages/zenn-cli/src/client/global.css
index 7d503fa8..022df245 100644
--- a/packages/zenn-cli/src/client/global.css
+++ b/packages/zenn-cli/src/client/global.css
@@ -100,6 +100,7 @@ code {
 }
 
 /* ツールチップ */
+/* Forked from Microtip https://github.com/ghosh/microtip */
 
 [aria-label][role~='tooltip'] {
   position: relative;