diff --git a/Gemfile.lock b/Gemfile.lock
old mode 100755
new mode 100644
index 983d617..6005388
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -51,6 +51,8 @@ GEM
       sassc (> 2.0.1, < 3.0)
     jekyll-seo-tag (2.6.1)
       jekyll (>= 3.3, < 5.0)
+    jekyll-sitemap (1.4.0)
+      jekyll (>= 3.7, < 5.0)
     jekyll-toc (0.13.1)
       jekyll (>= 3.7)
       nokogiri (~> 1.9)
@@ -100,7 +102,7 @@ GEM
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     thread_safe (0.3.6)
-    tzinfo (1.2.6)
+    tzinfo (1.2.10)
       thread_safe (~> 0.1)
     tzinfo-data (1.2019.3)
       tzinfo (>= 1.0.0)
@@ -120,6 +122,7 @@ DEPENDENCIES
   jekyll-relative-links
   jekyll-remote-theme
   jekyll-seo-tag
+  jekyll-sitemap
   jekyll-toc
   jekyll-twitter-plugin
   kramdown-math-katex