diff --git a/app/models/comment.rb b/app/models/comment.rb
index f9cd4dfc7..987516eeb 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -6,7 +6,7 @@ class Comment < ApplicationRecord
   has_many :moderation_reports, as: :model
   has_many :votes, :class_name => "CommentVote", :dependent => :destroy
 
-  validates :body, presence: true
+  validates :body, presence: true, length: { maximum: 15_000 }, if: :body_changed?
 
   before_create :autoreport_spam
   after_create :update_last_commented_at_on_create
diff --git a/app/models/dmail.rb b/app/models/dmail.rb
index 8a1eb81d6..fb5c8f40f 100644
--- a/app/models/dmail.rb
+++ b/app/models/dmail.rb
@@ -2,7 +2,8 @@ require 'digest/sha1'
 
 class Dmail < ApplicationRecord
   validate :validate_sender_is_not_limited, on: :create
-  validates_presence_of :title, :body, on: :create
+  validates :title, presence: true, length: { maximum: 200 }, if: :title_changed?
+  validates :body, presence: true, length: { maximum: 50_000 }, if: :body_changed?
 
   belongs_to :owner, :class_name => "User"
   belongs_to :to, :class_name => "User"
diff --git a/app/models/forum_post.rb b/app/models/forum_post.rb
index 79ffd795a..d195ad40b 100644
--- a/app/models/forum_post.rb
+++ b/app/models/forum_post.rb
@@ -1,8 +1,10 @@
 class ForumPost < ApplicationRecord
   attr_readonly :topic_id
+
   belongs_to :creator, class_name: "User"
   belongs_to_updater
   belongs_to :topic, class_name: "ForumTopic", inverse_of: :forum_posts
+
   has_many :dtext_links, as: :model, dependent: :destroy
   has_many :moderation_reports, as: :model
   has_many :votes, class_name: "ForumPostVote"
@@ -10,12 +12,13 @@ class ForumPost < ApplicationRecord
   has_one :tag_implication
   has_one :bulk_update_request
 
+  validates :body, presence: true, length: { maximum: 200_000 }, if: :body_changed?
+
   before_save :update_dtext_links, if: :dtext_links_changed?
   before_create :autoreport_spam
   after_create :update_topic_updated_at_on_create
   after_update :update_topic_updated_at_on_update_for_original_posts
   after_destroy :update_topic_updated_at_on_destroy
-  validates_presence_of :body
   after_save :delete_topic_if_original_post
   after_update(:if => ->(rec) {rec.updater_id != rec.creator_id}) do |rec|
     ModAction.log("#{CurrentUser.user.name} updated forum ##{rec.id}", :forum_post_update)
diff --git a/app/models/forum_topic.rb b/app/models/forum_topic.rb
index 8edbcee0d..35d3d4f6c 100644
--- a/app/models/forum_topic.rb
+++ b/app/models/forum_topic.rb
@@ -21,11 +21,11 @@ class ForumTopic < ApplicationRecord
   has_many :tag_aliases, :foreign_key => "forum_topic_id"
   has_many :tag_implications, :foreign_key => "forum_topic_id"
 
-  validates_presence_of :title
+  validates :title, presence: true, length: { maximum: 200 }, if: :title_changed?
   validates_associated :original_post
   validates_inclusion_of :category_id, :in => CATEGORIES.keys
   validates_inclusion_of :min_level, :in => MIN_LEVELS.values
-  validates :title, :length => {:maximum => 255}
+
   accepts_nested_attributes_for :original_post
   after_update :update_orignal_post
   after_save(:if => ->(rec) {rec.is_locked? && rec.saved_change_to_is_locked?}) do |rec|