diff --git a/app/models/issue.rb b/app/models/issue.rb
index b8b432673a4..3da595d91c2 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -2,7 +2,7 @@ class Issue < ActiveRecord::Base
   belongs_to :project
   belongs_to :author, :class_name => "User"
   belongs_to :assignee, :class_name => "User"
-  has_many :notes, :as => :noteable
+  has_many :notes, :as => :noteable, :dependent => :destroy
 
   attr_protected :author, :author_id, :project, :project_id
 
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 6f8b0cdfedd..d726d2d046d 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -2,7 +2,7 @@ class MergeRequest < ActiveRecord::Base
   belongs_to :project
   belongs_to :author, :class_name => "User"
   belongs_to :assignee, :class_name => "User"
-  has_many :notes, :as => :noteable
+  has_many :notes, :as => :noteable, :dependent => :destroy
 
   attr_protected :author, :author_id, :project, :project_id
 
diff --git a/app/models/snippet.rb b/app/models/snippet.rb
index d849a1d3f61..ae25e8a3bb8 100644
--- a/app/models/snippet.rb
+++ b/app/models/snippet.rb
@@ -3,7 +3,7 @@ class Snippet < ActiveRecord::Base
 
   belongs_to :project
   belongs_to :author, :class_name => "User"
-  has_many :notes, :as => :noteable
+  has_many :notes, :as => :noteable, :dependent => :destroy
 
   delegate :name,
            :email,