diff --git a/test/unit/lib/redmine/export/pdf_test.rb b/test/unit/lib/redmine/export/pdf_test.rb
index 371c0caac..14e4f96ee 100644
--- a/test/unit/lib/redmine/export/pdf_test.rb
+++ b/test/unit/lib/redmine/export/pdf_test.rb
@@ -18,8 +18,10 @@
 require File.expand_path('../../../../../test_helper', __FILE__)
 
 class PdfTest < ActiveSupport::TestCase
+  include Redmine::I18n
 
   def test_fix_text_encoding_backslash_ascii
+    set_language_if_valid 'ja'
     pdf = Redmine::Export::PDF::IFPDF.new('ja')
     assert pdf
     assert_equal '\\\\abcd', pdf.fix_text_encoding('\\abcd')