diff --git a/test/unit/mailer_test.rb b/test/unit/mailer_test.rb
index 18a045713..f39f3cdbe 100644
--- a/test/unit/mailer_test.rb
+++ b/test/unit/mailer_test.rb
@@ -470,7 +470,7 @@ class MailerTest < ActiveSupport::TestCase
     assert_equal 1, ActionMailer::Base.deliveries.size
     mail = last_email
     assert mail.bcc.include?('dlopper@somenet.foo')
-    assert mail.body.include?('Bug #3: Error 281 when updating a recipe')
+    assert mail.body.to_s.include?('Bug #3: Error 281 when updating a recipe')
     assert_equal '1 issue(s) due in the next 42 days', mail.subject
   end
 
@@ -496,7 +496,7 @@ class MailerTest < ActiveSupport::TestCase
     assert_equal 1, ActionMailer::Base.deliveries.size # No mail for dlopper
     mail = last_email
     assert mail.bcc.include?('dlopper@somenet.foo')
-    assert mail.body.include?('Bug #3: Error 281 when updating a recipe')
+    assert mail.body.to_s.include?('Bug #3: Error 281 when updating a recipe')
   end
 
   def last_email
@@ -514,7 +514,7 @@ class MailerTest < ActiveSupport::TestCase
     user.language = 'fr'
     Mailer.deliver_account_activated(user)
     mail = last_email
-    assert mail.body.include?('Votre compte')
+    assert mail.body.to_s.include?('Votre compte')
 
     assert_equal :it, current_language
   end