diff --git a/Gemfile b/Gemfile
index 0ce52e3..00020d4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -17,7 +17,7 @@ gem 'pg', '0.19.0'
 gem 'mysql2', '0.5.2'
 
 # App level
-gem 'devise', '3.5.2'
+gem 'devise', '4.8.1'
 
 gem 'colorize', '0.8.1'
 gem 'letter_opener', '1.4.1'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7888a0c..ca15f30 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -277,7 +277,7 @@ GEM
       sass (>= 3.3.0, < 3.5)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.2.0)
     connection_pool (2.2.5)
     crass (0.2.1)
     css_parser (1.7.1)
@@ -285,12 +285,11 @@ GEM
     database_cleaner (1.3.0)
     debug_inspector (1.1.0)
     debugger-linecache (1.2.0)
-    devise (3.5.2)
+    devise (4.8.1)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
-      railties (>= 3.2.6, < 5)
+      railties (>= 4.1.0)
       responders
-      thread_safe (~> 0.1)
       warden (~> 1.2.3)
     erubis (2.7.0)
     exception_notification (4.0.1)
@@ -325,13 +324,13 @@ GEM
       multi_xml (>= 0.5.2)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    image_optim (0.24.2)
+    image_optim (0.31.2)
       exifr (~> 1.2, >= 1.2.2)
       fspath (~> 3.0)
-      image_size (~> 1.5)
+      image_size (>= 1.5, < 4)
       in_threads (~> 1.3)
       progress (~> 3.0, >= 3.0.1)
-    image_size (1.5.0)
+    image_size (3.2.0)
     in_threads (1.6.0)
     innertube (1.1.0)
     jbuilder (1.0.2)
@@ -368,7 +367,7 @@ GEM
     mini_magick (4.2.7)
     mini_mime (1.1.2)
     mini_portile2 (2.3.0)
-    minitest (5.15.0)
+    minitest (5.17.0)
     minitest-rails (2.2.0)
       minitest (~> 5.7)
       railties (~> 4.1)
@@ -566,7 +565,7 @@ DEPENDENCIES
   compass-rails!
   crop_tool!
   database_cleaner (= 1.3.0)
-  devise (= 3.5.2)
+  devise (= 4.8.1)
   exception_notification (= 4.0.1)
   factory_girl (= 4.4.0)
   faker (= 1.4.3)
@@ -576,7 +575,7 @@ DEPENDENCIES
   friendly_id_pack!
   gibbon (= 1.1.5)
   haml (= 4.0.5)
-  image_optim (= 0.24.2)
+  image_optim (= 0.31.2)
   image_tools!
   jbuilder (= 1.0.2)
   jquery-rails (= 4.0.4)