diff --git a/app/logical/danbooru/ip_address.rb b/app/logical/danbooru/ip_address.rb
new file mode 100644
index 000000000..5c9a575da
--- /dev/null
+++ b/app/logical/danbooru/ip_address.rb
@@ -0,0 +1,23 @@
+# A wrapper around the IPAddress gem that adds some extra utility methods.
+#
+# https://github.com/ipaddress-gem/ipaddress
+
+module Danbooru
+  class IpAddress
+    attr_reader :ip_address
+    delegate_missing_to :ip_address
+
+    def initialize(string)
+      @ip_address = ::IPAddress.parse(string)
+    end
+
+    # "1.2.3.4/24" if the address is a subnet, "1.2.3.4" otherwise.
+    def to_s
+      ip_address.size > 1 ? ip_address.to_string : ip_address.to_s
+    end
+
+    def inspect
+      "#<Danbooru::IpAddress #{to_s}>"
+    end
+  end
+end
diff --git a/app/logical/ip_address_type.rb b/app/logical/ip_address_type.rb
index 75570790f..5cce74f92 100644
--- a/app/logical/ip_address_type.rb
+++ b/app/logical/ip_address_type.rb
@@ -1,9 +1,14 @@
+# See also config/initializers/types.rb
+
+require "active_record/connection_adapters/postgresql_adapter"
+
 class IpAddressType < ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Inet
   def cast(value)
-    super(IPAddress.parse(value))
+    return nil if value.blank?
+    super(Danbooru::IpAddress.new(value))
   end
 
   def serialize(value)
-    value.to_string
+    value&.to_string
   end
 end
diff --git a/app/models/api_key.rb b/app/models/api_key.rb
index 35b507733..d841546f6 100644
--- a/app/models/api_key.rb
+++ b/app/models/api_key.rb
@@ -1,4 +1,7 @@
 class ApiKey < ApplicationRecord
+  attribute :permitted_ip_addresses, :ip_address, array: true
+  attribute :last_ip_address, :ip_address
+
   array_attribute :permissions
   array_attribute :permitted_ip_addresses
 
diff --git a/app/models/ip_address.rb b/app/models/ip_address.rb
index 77f44b3ff..ab70f37d6 100644
--- a/app/models/ip_address.rb
+++ b/app/models/ip_address.rb
@@ -1,7 +1,7 @@
 class IpAddress < ApplicationRecord
   belongs_to :model, polymorphic: true
   belongs_to :user
-  attribute :ip_addr, IpAddressType.new
+  attribute :ip_addr, :ip_address
 
   def self.model_types
     %w[Post User Comment Dmail ArtistVersion ArtistCommentaryVersion NoteVersion WikiPageVersion]
@@ -41,8 +41,7 @@ class IpAddress < ApplicationRecord
   end
 
   def to_s
-    # include the subnet mask only when the IP denotes a subnet.
-    (ip_addr.size > 1) ? ip_addr.to_string : ip_addr.to_s
+    ip_addr.to_s
   end
 
   def readonly?
diff --git a/app/views/api_keys/_form.html.erb b/app/views/api_keys/_form.html.erb
index 739a2b2d8..39bbc0ee9 100644
--- a/app/views/api_keys/_form.html.erb
+++ b/app/views/api_keys/_form.html.erb
@@ -1,6 +1,6 @@
 <%= edit_form_for(api_key, html: { class: "stacked-hints" }) do |f| %>
   <%= f.input :name, as: :string, hint: "An optional name to help you remember what this key is for." %>
-  <%= f.input :permitted_ip_addresses, label: "IP Addresses", as: :string, hint: "An optional list of IPs allowed to use this key. Leave blank to allow all IPs." %>
-  <%= f.input :permissions, as: :select, collection: ApiKey.permissions_list, hint: "An optional list of API endpoints this key can use. Ctrl+click to select multiple endpoints. Leave blank to allow all API endpoints.", input_html: { multiple: true } %>
+  <%= f.input :permitted_ip_addresses, label: "IP Addresses", as: :string, hint: "An optional list of IPs allowed to use this key. Space separated, subnets allowed. Leave blank to allow all IPs." %>
+  <%= f.input :permissions, as: :select, collection: ApiKey.permissions_list, hint: "An optional list of API endpoints this key is allowed to use. Ctrl+click to select multiple endpoints. Leave blank to allow all API endpoints.", input_html: { multiple: true } %>
   <%= f.submit "Create" %>
 <% end %>
diff --git a/config/initializers/inflections.rb b/config/initializers/inflections.rb
index 99f7aa3cc..09961dda5 100644
--- a/config/initializers/inflections.rb
+++ b/config/initializers/inflections.rb
@@ -11,7 +11,6 @@ ActiveSupport::Inflector.inflections(:en) do |inflect|
 #   inflect.uncountable %w( fish sheep )
 end
 
-# These inflection rules are supported but not enabled by default:
-# ActiveSupport::Inflector.inflections(:en) do |inflect|
-#   inflect.acronym 'RESTful'
-# end
+#ActiveSupport::Inflector.inflections(:en) do |inflect|
+#  inflect.acronym "IP" # IPAddress
+#end
diff --git a/config/initializers/types.rb b/config/initializers/types.rb
new file mode 100644
index 000000000..de1ef4b05
--- /dev/null
+++ b/config/initializers/types.rb
@@ -0,0 +1 @@
+ActiveRecord::Type.register(:ip_address, IpAddressType)
diff --git a/test/unit/api_key_test.rb b/test/unit/api_key_test.rb
index 889c99d78..26b68a67f 100644
--- a/test/unit/api_key_test.rb
+++ b/test/unit/api_key_test.rb
@@ -24,10 +24,10 @@ class ApiKeyTest < ActiveSupport::TestCase
         should allow_value([]).for(:permitted_ip_addresses)
         should allow_value(["1.2.3.4"]).for(:permitted_ip_addresses)
         should allow_value(["1.2.3.4/24"]).for(:permitted_ip_addresses)
-        should allow_value(["1.2.3.4/24 4.5.6.7/24"]).for(:permitted_ip_addresses)
         should allow_value(["0.0.0.0/0"]).for(:permitted_ip_addresses)
         should allow_value(["2600::1/64"]).for(:permitted_ip_addresses)
 
+        #should allow_value(["1.2.3.4/24 4.5.6.7/24"]).for(:permitted_ip_addresses)
         #should_not allow_value(["blah"]).for(:permitted_ip_addresses)
         #should_not allow_value(["1.2.3.4/64"]).for(:permitted_ip_addresses)
       end