diff --git a/app/models/room.rb b/app/models/room.rb
index 6c6958a2..4e948f67 100644
--- a/app/models/room.rb
+++ b/app/models/room.rb
@@ -1,3 +1,4 @@
 class Room < ApplicationRecord
-  has_many :room_messages, dependent: :destroy
+  has_many :room_messages, dependent: :destroy,
+                           inverse_of: :room
 end
diff --git a/app/models/room_message.rb b/app/models/room_message.rb
index 16aace3d..6ab75e98 100644
--- a/app/models/room_message.rb
+++ b/app/models/room_message.rb
@@ -1,5 +1,6 @@
 class RoomMessage < ApplicationRecord
-  belongs_to :room
+  belongs_to :room, inverse_of: :room_messages
+
   belongs_to :user
 
   def as_json(options)
diff --git a/app/views/devise/registrations/new.html.erb b/app/views/devise/registrations/new.html.erb
index 41ade0a7..2b61d5b4 100644
--- a/app/views/devise/registrations/new.html.erb
+++ b/app/views/devise/registrations/new.html.erb
@@ -20,7 +20,7 @@
   </div>
 
   <div class="form-actions">
-    <%= f.button :submit, "Sign up", class: 'btn-success' %>
+    <%= f.button :submit, "Sign up", class: 'btn btn-success' %>
   </div>
 <% end %>
 
diff --git a/app/views/rooms/index.html.erb b/app/views/rooms/index.html.erb
index d1e09069..b62d3d52 100644
--- a/app/views/rooms/index.html.erb
+++ b/app/views/rooms/index.html.erb
@@ -1,5 +1,5 @@
 <div class="row">
-  <div class="col-12 col-md-3 text-cebter">
+  <div class="col-12 col-md-3">
     <%= render partial: 'rooms' %>
   </div>