diff --git a/.rubocop.yml b/.rubocop.yml
index f1ea14e8cc..05dd2cc324 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -227,7 +227,7 @@ Style/StringLiteralsInInterpolation:
   EnforcedStyle: double_quotes
 
 Style/TrailingCommaInArguments:
-  EnforcedStyleForMultiline: comma
+  Enabled: false
 
 Style/TrailingCommaInArrayLiteral:
   EnforcedStyleForMultiline: comma
diff --git a/app/helpers/alchemy/admin/pictures_helper.rb b/app/helpers/alchemy/admin/pictures_helper.rb
index a920f17ecc..d2c5f47cc4 100644
--- a/app/helpers/alchemy/admin/pictures_helper.rb
+++ b/app/helpers/alchemy/admin/pictures_helper.rb
@@ -4,12 +4,10 @@ module Alchemy
   module Admin
     module PicturesHelper
       def preview_size(size)
-        case size
-        when "small" then "80x60"
-        when "large" then "240x180"
-        else
-          "160x120"
-        end
+        Alchemy::Picture::THUMBNAIL_SIZES.fetch(
+          size,
+          Alchemy::Picture::THUMBNAIL_SIZES[:medium]
+        )
       end
     end
   end
diff --git a/app/models/alchemy/picture.rb b/app/models/alchemy/picture.rb
index c9d5b26d8d..961f14805f 100644
--- a/app/models/alchemy/picture.rb
+++ b/app/models/alchemy/picture.rb
@@ -22,6 +22,12 @@
 
 module Alchemy
   class Picture < BaseRecord
+    THUMBNAIL_SIZES = {
+      small: "80x60",
+      medium: "160x120",
+      large: "240x180",
+    }.with_indifferent_access.freeze
+
     CONVERTIBLE_FILE_FORMATS = %w(gif jpg jpeg png).freeze
 
     include Alchemy::NameConversions