diff --git a/Gemfile.lock b/Gemfile.lock
index 3ab623f..9b6aa74 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -11,8 +11,8 @@ GEM
   remote: https://rubygems.org/
   specs:
     Ascii85 (1.0.3)
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.8.0)
+      public_suffix (>= 2.0.2, < 5.0)
     afm (0.2.2)
     asciidoctor (1.5.6.1)
     asciidoctor-pdf (1.5.0.alpha.16)
@@ -63,7 +63,7 @@ GEM
     prawn-templates (0.1.1)
       pdf-reader (~> 2.0)
       prawn (~> 2.2)
-    public_suffix (3.0.2)
+    public_suffix (4.0.6)
     pygments.rb (1.2.1)
       multi_json (>= 1.0.0)
     rake (12.3.3)