diff --git a/app/models/issue.rb b/app/models/issue.rb
index 5c1911eb8d..4faa063762 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1679,8 +1679,28 @@ class Issue < ActiveRecord::Base
   end
 
   def after_project_change
-    # Update project_id on related time entries
-    TimeEntry.where({:issue_id => id}).update_all(["project_id = ?", project_id])
+    # Update project_id and activity_id on related time entries
+    activities = project.activities
+    time_entries.each do |time_entry|
+      curr_activity = time_entry.activity
+      curr_activity_id = (curr_activity.parent_id || curr_activity.id)
+      new_activity =
+        activities.detect do |activity|
+          activity.id == curr_activity_id || activity.parent_id == curr_activity_id
+        end
+
+      time_entry.project = project
+      time_entry.activity = new_activity unless curr_activity == new_activity
+      unless time_entry.save
+        errors.add(
+          :base,
+          l(:error_move_of_time_entries_not_possible,
+            :id => "##{time_entry.id}",
+            :errors => time_entry.errors.full_messages.join(", "))
+        )
+        raise ActiveRecord::Rollback
+      end
+    end
 
     # Delete issue relations
     unless Setting.cross_project_issue_relations?
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 2eb4af0e13..8693538ac1 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -229,6 +229,7 @@ en:
   error_no_tracker_allowed_for_new_issue_in_project: "The project doesn't have any trackers for which you can create an issue"
   error_no_projects_with_tracker_allowed_for_new_issue: "There are no projects with trackers for which you can create an issue"
   error_move_of_child_not_possible: "Subtask %{child} could not be moved to the new project: %{errors}"
+  error_move_of_time_entries_not_possible: "Spent time %{id} could not be moved to the new project: %{errors}"
   error_cannot_reassign_time_entries_to_an_issue_about_to_be_deleted: "Spent time cannot be reassigned to an issue that is about to be deleted"
   warning_fields_cleared_on_bulk_edit: "Changes will result in the automatic deletion of values from one or more fields on the selected objects"
   error_exceeds_maximum_hours_per_day: "Cannot log more than %{max_hours} hours on the same day (%{logged_hours} hours have already been logged)"
diff --git a/test/unit/issue_test.rb b/test/unit/issue_test.rb
index cc53598622..255476754f 100644
--- a/test/unit/issue_test.rb
+++ b/test/unit/issue_test.rb
@@ -1550,6 +1550,35 @@ class IssueTest < ActiveSupport::TestCase
     issue.save!
   end
 
+  def test_after_project_change_should_update_project_and_activity_of_time_entries
+    time_entry = TimeEntry.find(3)
+    assert_equal [1, 9], [time_entry.project_id, time_entry.activity_id]
+
+    activity = TimeEntryActivity.create!(:name => 'Design', :parent_id => 9, :project_id => 3)
+    issue = Issue.find(3)
+    issue.project = Project.find(3)
+
+    assert issue.save
+
+    time_entry.reload
+    assert_equal [3, activity.id], [time_entry.project_id, time_entry.activity_id]
+  end
+
+  def test_after_project_change_should_not_update_project_and_activity_of_time_entries_when_activity_is_inactive
+    time_entry = TimeEntry.find(3)
+    assert_equal [1, 9], [time_entry.project_id, time_entry.activity_id]
+
+    TimeEntryActivity.create!(:name => 'Design', :active => false, :parent_id => 9, :project_id => 3)
+    issue = Issue.find(3)
+    issue.project = Project.find(3)
+
+    assert !issue.save
+    assert_match /\ASpent time #3 could not be moved to the new project:/, issue.errors.full_messages.first
+
+    time_entry.reload
+    assert_equal [1, 9], [time_entry.project_id, time_entry.activity_id]
+  end
+
   def test_adding_journal_should_update_timestamp
     issue = Issue.find(1)
     updated_on_was = issue.updated_on