diff --git a/app/models/enumeration.rb b/app/models/enumeration.rb
index 4710fde81..dfa6ba49f 100644
--- a/app/models/enumeration.rb
+++ b/app/models/enumeration.rb
@@ -24,7 +24,7 @@ class Enumeration < ActiveRecord::Base
 
   belongs_to :project
 
-  acts_as_positioned :scope => :parent_id
+  acts_as_positioned :scope => %i[project_id parent_id]
   acts_as_customizable
   acts_as_tree
 
@@ -149,7 +149,7 @@ class Enumeration < ActiveRecord::Base
   # position as the overridden enumeration
   def update_position
     super
-    if saved_change_to_position?
+    if saved_change_to_position? && self.parent_id.nil?
       self.class.where.not(:parent_id => nil).update_all(
         "position = coalesce((
           select position
diff --git a/test/unit/time_entry_activity_test.rb b/test/unit/time_entry_activity_test.rb
index 9a338b4ce..0a5cbdd17 100644
--- a/test/unit/time_entry_activity_test.rb
+++ b/test/unit/time_entry_activity_test.rb
@@ -131,4 +131,24 @@ class TimeEntryActivityTest < ActiveSupport::TestCase
     assert_include activity, project.activities
     assert_include TimeEntryActivity.find(9), project.activities
   end
+
+  def test_project_activity_should_have_the_same_position_as_the_position_of_the_parent_activity
+    project = Project.find(1)
+
+    parent_activity = TimeEntryActivity.find_by(position: 3, parent_id: nil)
+    project.update_or_create_time_entry_activities({parent_activity.id.to_s => {'parent_id' => parent_activity.id.to_s, 'active' => '0', 'custom_field_values' => {'7' => ''}}})
+    project_activity = TimeEntryActivity.find_by(position: 3, parent_id: parent_activity.id, project_id: 1)
+    assert_equal parent_activity.position, project_activity.position
+
+    # Changing the position of the parent activity also changes the position of the activity in each project.
+    other_parent_activity = TimeEntryActivity.find_by(position: 4, parent_id: nil)
+    project.update_or_create_time_entry_activities({other_parent_activity.id.to_s => {'parent_id' => other_parent_activity.id.to_s, 'active' => '0', 'custom_field_values' => {'7' => ''}}})
+    other_project_activity = TimeEntryActivity.find_by(position: 4, parent_id: other_parent_activity.id, project_id: 1)
+
+    parent_activity.update(position: 4)
+    assert_equal 4, parent_activity.reload.position
+    assert_equal parent_activity.position, project_activity.reload.position
+    assert_equal 3, other_parent_activity.reload.position
+    assert_equal other_parent_activity.position, other_project_activity.reload.position
+  end
 end