diff --git a/test/functional/issues_controller_test.rb b/test/functional/issues_controller_test.rb
index f85d157ce..76f9586af 100644
--- a/test/functional/issues_controller_test.rb
+++ b/test/functional/issues_controller_test.rb
@@ -2168,7 +2168,7 @@ class IssuesControllerTest < ActionController::TestCase
     mail = ActionMailer::Base.deliveries.last
     assert_not_nil mail
     assert mail.subject.starts_with?("[#{issue.project.name} - #{issue.tracker.name} ##{issue.id}]")
-    assert mail.body.include?("Subject changed from #{old_subject} to #{new_subject}")
+    assert mail.body.to_s.include?("Subject changed from #{old_subject} to #{new_subject}")
   end
 
   def test_put_update_with_project_change
@@ -2242,7 +2242,7 @@ class IssuesControllerTest < ActionController::TestCase
 
     mail = ActionMailer::Base.deliveries.last
     assert_not_nil mail
-    assert mail.body.include?("Searchable field changed from 125 to New custom value")
+    assert mail.body.to_s.include?("Searchable field changed from 125 to New custom value")
   end
 
   def test_put_update_with_multi_custom_field_change
@@ -2285,7 +2285,7 @@ class IssuesControllerTest < ActionController::TestCase
     assert_equal 2, j.details.size
 
     mail = ActionMailer::Base.deliveries.last
-    assert mail.body.include?("Status changed from New to Assigned")
+    assert mail.body.to_s.include?("Status changed from New to Assigned")
     # subject should contain the new status
     assert mail.subject.include?("(#{ IssueStatus.find(2).name })")
   end
@@ -2303,7 +2303,7 @@ class IssuesControllerTest < ActionController::TestCase
     assert_equal User.anonymous, j.user
 
     mail = ActionMailer::Base.deliveries.last
-    assert mail.body.include?(notes)
+    assert mail.body.to_s.include?(notes)
   end
 
   def test_put_update_with_note_and_spent_time
@@ -2361,7 +2361,7 @@ class IssuesControllerTest < ActionController::TestCase
     assert_equal 59, File.size(attachment.diskfile)
 
     mail = ActionMailer::Base.deliveries.last
-    assert mail.body.include?('testfile.txt')
+    assert mail.body.to_s.include?('testfile.txt')
   end
 
   def test_put_update_with_failure_should_save_attachments