diff --git a/Gemfile b/Gemfile
index 7ea5fbf8..a1008a3a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,5 +5,5 @@ source "https://rubygems.org"
 gem "jekyll", "~> 4.2"
 gem "mdl", "~> 0.11.0"
 gem "rake", "~> 13.0"
-gem "rdoc", "~> 6.3"
+gem "rdoc", "~> 6.4"
 gem "webrick", "~> 1.7"
diff --git a/Gemfile.lock b/Gemfile.lock
index 8f4352d9..dcee3926 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -57,21 +57,23 @@ GEM
       chef-utils
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    psych (4.0.3)
+    psych (5.1.2)
       stringio
     public_suffix (4.0.6)
     rake (13.0.6)
     rb-fsevent (0.11.0)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rdoc (6.4.0)
+    rdoc (6.4.1.1)
       psych (>= 4.0.0)
-    rexml (3.2.5)
+    rexml (3.2.8)
+      strscan (>= 3.0.9)
     rouge (3.27.0)
     safe_yaml (1.0.5)
     sassc (2.4.0)
       ffi (~> 1.9)
-    stringio (3.0.1)
+    stringio (3.1.0)
+    strscan (3.1.0)
     terminal-table (2.0.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     tomlrb (2.0.1)
@@ -86,7 +88,7 @@ DEPENDENCIES
   jekyll (~> 4.2)
   mdl (~> 0.11.0)
   rake (~> 13.0)
-  rdoc (~> 6.3)
+  rdoc (~> 6.4)
   webrick (~> 1.7)
 
 BUNDLED WITH