diff --git a/docs/installation.md b/docs/installation.md
index e2c3d56..e67d534 100644
--- a/docs/installation.md
+++ b/docs/installation.md
@@ -13,6 +13,8 @@
     - jekyll-seo-tag
   ```
 
+If you are using a Jekyll version less than `3.5.0`, use the `gems` key instead of `plugins`.
+
 3. Add the following right before `</head>` in your site's template(s):
 
   ```liquid