diff --git a/images/Gemfile.lock b/images/Gemfile.lock
index d3a490a..b2a941c 100644
--- a/images/Gemfile.lock
+++ b/images/Gemfile.lock
@@ -6,7 +6,7 @@ GEM
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
-    addressable (2.7.0)
+    addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     awesome_print (1.8.0)
     aws-s3 (0.6.3)
@@ -96,7 +96,7 @@ GEM
     piet (0.2.6)
       png_quantizator
     png_quantizator (0.2.1)
-    public_suffix (4.0.3)
+    public_suffix (4.0.6)
     representable (3.0.4)
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
@@ -123,7 +123,6 @@ GEM
       faraday (~> 0.9)
       jwt (>= 1.5, < 3.0)
       multi_json (~> 1.10)
-    slack-notifier (2.3.2)
     thread_safe (0.3.6)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
@@ -156,7 +155,6 @@ DEPENDENCIES
   piet
   rmagick
   rspec
-  slack-notifier
   vcr
   webmock