diff --git a/example/sinatra/Gemfile.lock b/example/sinatra/Gemfile.lock
index e6e4779..b10c631 100644
--- a/example/sinatra/Gemfile.lock
+++ b/example/sinatra/Gemfile.lock
@@ -8,8 +8,8 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.8.1)
+      public_suffix (>= 2.0.2, < 6.0)
     bcrypt (3.1.12)
     bcrypt-ruby (3.1.5)
       bcrypt (>= 3.1.3)
@@ -70,7 +70,7 @@ GEM
     json-api-vanilla (1.0.1)
     json_pure (1.8.6)
     multi_json (1.13.1)
-    public_suffix (3.0.2)
+    public_suffix (5.0.0)
     rack (1.6.10)
     rack-protection (1.5.5)
       rack