diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 6966204..1a40f5e 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -73,7 +73,7 @@ class ApplicationController < ActionController::Base
     APIUsage.create!(
       user_id:    CurrentUser.is_anonymous? ? nil : CurrentUser.id,
       api_key:    @apikey.nil? || @apikey.is_anon? ? nil : @apikey,
-      user_agent: request.headers["user-agent"],
+      user_agent: request.headers["user-agent"] || "",
       method:     request.method,
       path:       request.path,
       params:     request.params.to_json,
diff --git a/app/controllers/exceptions_controller.rb b/app/controllers/exceptions_controller.rb
index 08111dd..340e4b9 100644
--- a/app/controllers/exceptions_controller.rb
+++ b/app/controllers/exceptions_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ExceptionsController < ApplicationController
   def index
     @pagy, @exceptions = pagy(ExceptionLog.order(id: :desc), items: 25)
diff --git a/app/logical/pool_index.rb b/app/logical/pool_index.rb
index dd72536..7a3cbbd 100644
--- a/app/logical/pool_index.rb
+++ b/app/logical/pool_index.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module PoolIndex
   module_function
 
diff --git a/app/models/api_image.rb b/app/models/api_image.rb
index 30af06b..c761bb6 100644
--- a/app/models/api_image.rb
+++ b/app/models/api_image.rb
@@ -35,7 +35,7 @@ class APIImage < ApplicationRecord
     invalidate_cache
   end
 
-  def  file_header_info(file_path)
+  def file_header_info(file_path)
     File.open(file_path) do |bin|
       mime_type = Marcel::MimeType.for(bin)
       ext = case mime_type
diff --git a/app/models/e621/pool.rb b/app/models/e621/pool.rb
index 968880a..5dd986f 100644
--- a/app/models/e621/pool.rb
+++ b/app/models/e621/pool.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class Pool < ApplicationRecord
     self.table_name = "e621.pools"
diff --git a/app/models/e621/post.rb b/app/models/e621/post.rb
index 143dcad..b82242a 100644
--- a/app/models/e621/post.rb
+++ b/app/models/e621/post.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class Post < ApplicationRecord
     self.table_name = "e621.posts"
diff --git a/app/models/e621/tag.rb b/app/models/e621/tag.rb
index d11df46..1cc386a 100644
--- a/app/models/e621/tag.rb
+++ b/app/models/e621/tag.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class Tag < ApplicationRecord
     self.table_name = "e621.tags"
diff --git a/app/models/e621/tag_alias.rb b/app/models/e621/tag_alias.rb
index b57c026..1b5ec2c 100644
--- a/app/models/e621/tag_alias.rb
+++ b/app/models/e621/tag_alias.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class TagAlias < ApplicationRecord
     self.table_name = "e621.tag_aliases"
diff --git a/app/models/e621/tag_implication.rb b/app/models/e621/tag_implication.rb
index d78d407..0931e87 100644
--- a/app/models/e621/tag_implication.rb
+++ b/app/models/e621/tag_implication.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class TagImplication < ApplicationRecord
     self.table_name = "e621.tag_implications"
diff --git a/app/models/e621/wiki_page.rb b/app/models/e621/wiki_page.rb
index 00eee6f..efeef05 100644
--- a/app/models/e621/wiki_page.rb
+++ b/app/models/e621/wiki_page.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module E621
   class WikiPage < ApplicationRecord
     self.table_name = "e621.wiki_pages"
diff --git a/app/models/exception_log.rb b/app/models/exception_log.rb
index 1fe140b..3e343f8 100644
--- a/app/models/exception_log.rb
+++ b/app/models/exception_log.rb
@@ -8,7 +8,7 @@ class ExceptionLog < ApplicationRecord
       host:       Socket.gethostname,
       params:     request.filtered_parameters,
       referrer:   request.referrer,
-      user_agent: request.user_agent,
+      user_agent: request.user_agent || "",
     }
 
     # Required to unwrap exceptions that occur inside template rendering.
diff --git a/config/initializers/cache_store.rb b/config/initializers/cache_store.rb
index 95eea25..ccb124b 100644
--- a/config/initializers/cache_store.rb
+++ b/config/initializers/cache_store.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 def cache_store
   [:memory_store, { size: 64.megabytes }]
 end
diff --git a/config/initializers/git_helper.rb b/config/initializers/git_helper.rb
index cc17ad1..70e6f08 100644
--- a/config/initializers/git_helper.rb
+++ b/config/initializers/git_helper.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
-#
+
 Rails.configuration.to_prepare do
   GitHelper.init
 end
diff --git a/db/migrate/20240603083428_create_e621_export_tables.rb b/db/migrate/20240603083428_create_e621_export_tables.rb
index e355fef..a14c2b2 100644
--- a/db/migrate/20240603083428_create_e621_export_tables.rb
+++ b/db/migrate/20240603083428_create_e621_export_tables.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateE621ExportTables < ActiveRecord::Migration[7.1]
   def change
     reversible do |r|
diff --git a/db/migrate/20240604105520_add_e621_pools_tag_string.rb b/db/migrate/20240604105520_add_e621_pools_tag_string.rb
index cf2a3a9..0b75601 100644
--- a/db/migrate/20240604105520_add_e621_pools_tag_string.rb
+++ b/db/migrate/20240604105520_add_e621_pools_tag_string.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AddE621PoolsTagString < ActiveRecord::Migration[7.1]
   def change
     add_column(:"e621.pools", :tag_string, :string, null: false, default: "")