diff --git a/mkdocs.yml b/mkdocs.yml
index a84eeb2..f6c7616 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -17,7 +17,7 @@ markdown_extensions:
 
 theme:
   name: "material"
-  language: "kr"
+  # language: "kr"
   extra:
     search:
       language: "en"
diff --git a/requirements.txt b/requirements.txt
index 5266dbb..f599533 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,7 @@
 
 mkdocs
-mkdocs-material
+mkdocs-material>=9.0
+mkdocs-material-extensions
+
+markdown
+Pygments # https://pygments.org/