diff --git a/LTI-Introduction/Gemfile.lock b/LTI-Introduction/Gemfile.lock
index d7133a2..5b0b6d3 100644
--- a/LTI-Introduction/Gemfile.lock
+++ b/LTI-Introduction/Gemfile.lock
@@ -38,8 +38,8 @@ GEM
       i18n (~> 0.7)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
-    addressable (2.5.2)
-      public_suffix (>= 2.0.2, < 4.0)
+    addressable (2.8.0)
+      public_suffix (>= 2.0.2, < 5.0)
     arel (8.0.0)
     autoprefixer-rails (8.0.0)
       execjs
@@ -95,7 +95,7 @@ GEM
     nio4r (2.2.0)
     nokogiri (1.10.4)
       mini_portile2 (~> 2.4.0)
-    public_suffix (3.0.2)
+    public_suffix (4.0.6)
     rack (2.0.8)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)