diff --git a/app/models/article.rb b/app/models/article.rb
index cac851160b0..45125df5a2d 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -31,7 +31,7 @@ class Article < ApplicationRecord
   validates :thumbnail_type, presence: true
   validates :published_at, presence: true, if: :will_be_published?
   validates :thumbnail,
-            content_type: %w[image/png image/jpg image/jpeg],
+            content_type: %w[image/png image/jpeg],
             size: { less_than: 10.megabytes }
 
   paginates_per 24
diff --git a/app/models/book.rb b/app/models/book.rb
index 797c0002f7c..8b7bc4fd8a9 100644
--- a/app/models/book.rb
+++ b/app/models/book.rb
@@ -11,7 +11,7 @@ class Book < ApplicationRecord
   validates :price, presence: true, numericality: { only_integer: true }
   validates :page_url, presence: true
   validates :cover,
-            content_type: %w[image/png image/jpg image/jpeg],
+            content_type: %w[image/png image/jpeg],
             size: { less_than: 10.megabytes }
 
   def cover_url
diff --git a/app/models/user.rb b/app/models/user.rb
index a8cd9f26448..d600e2e9d80 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -882,7 +882,7 @@ def validate_uploaded_avatar_content_type
     return unless uploaded_avatar
 
     mime_type = Marcel::Magic.by_magic(uploaded_avatar)&.type
-    return if mime_type&.start_with?('image/png', 'image/jpg', 'image/jpeg', 'image/gif', 'image/heic', 'image/heif')
+    return if mime_type&.start_with?('image/png', 'image/jpeg', 'image/gif', 'image/heic', 'image/heif')
 
     errors.add(:avatar, 'は指定された拡張子(PNG, JPG, JPEG, GIF, HEIC, HEIF形式)になっていないか、あるいは画像が破損している可能性があります')
   end
diff --git a/app/models/work.rb b/app/models/work.rb
index 6708f0a152a..cc88313f926 100644
--- a/app/models/work.rb
+++ b/app/models/work.rb
@@ -18,7 +18,7 @@ class Work < ApplicationRecord
               message: 'は「http://example.com」や「https://example.com」のようなURL形式で入力してください'
             }
   validates :thumbnail,
-            content_type: %w[image/png image/jpg image/jpeg],
+            content_type: %w[image/png image/jpeg],
             size: { less_than: 10.megabytes }
 
   def thumbnail_url