diff --git a/Gemfile b/Gemfile
index b56eff29d3..c7155eee2e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -56,7 +56,7 @@ gem 'friendly_id', '~> 5.2.1'
 gem 'acts_as_list', '~> 0.9.9'
 gem 'acts_as_tree', '~> 2.7.0'
 gem 'awesome_nested_set', '~> 3.1.3'
-gem 'typed_dag', '~> 2.0.0'
+gem 'typed_dag', '~> 2.0.1'
 
 gem 'color-tools', '~> 1.3.0', require: 'color'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 9cbffdb3f8..cdefad2dab 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -568,7 +568,7 @@ GEM
     tilt (2.0.7)
     timecop (0.9.1)
     ttfunk (1.5.0)
-    typed_dag (2.0.0)
+    typed_dag (2.0.1)
       rails (>= 5.0.4)
     tzinfo (1.2.3)
       thread_safe (~> 0.1)
@@ -719,7 +719,7 @@ DEPENDENCIES
   thin (~> 1.7.2)
   timecop (~> 0.9.0)
   transactional_lock!
-  typed_dag (~> 2.0.0)
+  typed_dag (~> 2.0.1)
   tzinfo-data (~> 1.2017.2)
   unicorn
   unicorn-worker-killer
diff --git a/app/contracts/relations/update_contract.rb b/app/contracts/relations/update_contract.rb
index 1ce941fa6e..d7b4a2c7be 100644
--- a/app/contracts/relations/update_contract.rb
+++ b/app/contracts/relations/update_contract.rb
@@ -32,17 +32,29 @@ require 'relations/base_contract'
 
 module Relations
   class UpdateContract < BaseContract
-    def validate
-      links_immutable
+    validate :from_immutable
+    validate :to_immutable
 
-      super
+    private
+
+    def from_immutable
+      errors.add :from, :error_readonly if from_id_changed_and_not_swapped?
     end
 
-    private
+    def to_immutable
+      errors.add :to, :error_readonly if to_id_changed_and_not_swapped?
+    end
+
+    def from_id_changed_and_not_swapped?
+      model.from_id_changed? && !from_and_to_swapped?
+    end
+
+    def to_id_changed_and_not_swapped?
+      model.to_id_changed? && !from_and_to_swapped?
+    end
 
-    def links_immutable
-      errors.add :from, :error_readonly if model.from_id_changed?
-      errors.add :to, :error_readonly if model.to_id_changed?
+    def from_and_to_swapped?
+      model.to_id == model.from_id_was && model.from_id == model.to_id_was
     end
   end
 end
diff --git a/spec/features/work_packages/details/details_relations_spec.rb b/spec/features/work_packages/details/details_relations_spec.rb
index 535477b795..1c86cfca21 100644
--- a/spec/features/work_packages/details/details_relations_spec.rb
+++ b/spec/features/work_packages/details/details_relations_spec.rb
@@ -137,17 +137,31 @@ describe 'Work package relations tab', js: true, selenium: true do
       find(toggle_btn_selector).click
       expect(page).to have_selector(toggle_btn_selector, text: 'Group by relation type', wait: 10)
 
+      # Expect current to be follows and other one related
       expect(page).to have_selector('.relation-row--type', text: 'Follows')
       expect(page).to have_selector('.relation-row--type', text: 'Related To')
 
-      # Expect current to be follows, then edit to blocks
+      # edit to blocks
       relations.edit_relation_type(to_1, to_type: 'Blocks')
 
+      # the other one should not be altered
       expect(page).to have_selector('.relation-row--type', text: 'Blocks')
       expect(page).to have_selector('.relation-row--type', text: 'Related To')
 
       updated_relation = Relation.find(relation_1.id)
       expect(updated_relation.relation_type).to eq('blocks')
+      expect(updated_relation.from_id).to eq(work_package.id)
+      expect(updated_relation.to_id).to eq(to_1.id)
+
+      relations.edit_relation_type(to_1, to_type: 'Blocked by')
+
+      expect(page).to have_selector('.relation-row--type', text: 'Blocked by')
+      expect(page).to have_selector('.relation-row--type', text: 'Related To')
+
+      updated_relation = Relation.find(relation_1.id)
+      expect(updated_relation.relation_type).to eq('blocks')
+      expect(updated_relation.from_id).to eq(to_1.id)
+      expect(updated_relation.to_id).to eq(work_package.id)
     end
   end