diff --git a/lib/plugins/rfpdf/lib/tcpdf.rb b/lib/plugins/rfpdf/lib/tcpdf.rb
index 7c4d0df81..287e81bb7 100755
--- a/lib/plugins/rfpdf/lib/tcpdf.rb
+++ b/lib/plugins/rfpdf/lib/tcpdf.rb
@@ -86,10 +86,10 @@ class TCPDF
   @@k_small_ratio = 2/3.0
   
   cattr_accessor :k_path_cache
-  @@k_path_cache = Rails.root.join('tmp').to_path
+  @@k_path_cache = Rails.root.join('tmp').to_s
   
   cattr_accessor :k_path_url_cache
-  @@k_path_url_cache = Rails.root.join('tmp').to_path
+  @@k_path_url_cache = Rails.root.join('tmp').to_s
   
   cattr_accessor :decoder
 		
diff --git a/lib/redmine/export/pdf.rb b/lib/redmine/export/pdf.rb
index f6988db79..899411a53 100644
--- a/lib/redmine/export/pdf.rb
+++ b/lib/redmine/export/pdf.rb
@@ -36,7 +36,7 @@ module Redmine
         attr_accessor :footer_date
 
         def initialize(lang)
-          @@k_path_cache = Rails.root.join('tmp', 'pdf').to_path
+          @@k_path_cache = Rails.root.join('tmp', 'pdf').to_s
           FileUtils.mkdir_p @@k_path_cache unless File::exist?(@@k_path_cache)
           set_language_if_valid lang
           pdf_encoding = l(:general_pdf_encoding).upcase