diff --git a/app/models/issue.rb b/app/models/issue.rb
index 4dcc69a..a23d4bd 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -66,7 +66,10 @@ class Issue < ActiveRecord::Base
   attr_reader :current_journal
   delegate :notes, :notes=, :private_notes, :private_notes=, :to => :current_journal, :allow_nil => true
 
-  validates_presence_of :subject, :priority, :project, :tracker, :author, :status
+  validates_presence_of :subject, :project, :tracker
+  validates_presence_of :priority, :if => Proc.new {|issue| issue.new_record? || issue.priority_id_changed?}
+  validates_presence_of :status, :if => Proc.new {|issue| issue.new_record? || issue.status_id_changed?}
+  validates_presence_of :author, :if => Proc.new {|issue| issue.new_record? || issue.author_id_changed?}
 
   validates_length_of :subject, :maximum => 255
   validates_inclusion_of :done_ratio, :in => 0..100
diff --git a/app/models/project.rb b/app/models/project.rb
index 961fb5b..f7cfc65 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -72,8 +72,7 @@ class Project < ActiveRecord::Base
   attr_protected :status
 
   validates_presence_of :name, :identifier
-  validates_uniqueness_of :identifier
-  validates_associated :repository, :wiki
+  validates_uniqueness_of :identifier, :if => Proc.new {|p| p.identifier_changed?}
   validates_length_of :name, :maximum => 255
   validates_length_of :homepage, :maximum => 255
   validates_length_of :identifier, :in => 1..IDENTIFIER_MAX_LENGTH