diff --git a/lib/redmine/export/pdf.rb b/lib/redmine/export/pdf.rb
index a7fd56aa8..55ab37da4 100644
--- a/lib/redmine/export/pdf.rb
+++ b/lib/redmine/export/pdf.rb
@@ -143,12 +143,19 @@ module Redmine
         end
 
         def fix_text_encoding(txt)
-          @ic ||= Iconv.new(l(:general_pdf_encoding), 'UTF-8')
-          txt = begin
-            @ic.iconv(txt)
-          rescue
-            txt
-          end || ''
+          if txt.respond_to?(:force_encoding)
+            txt.force_encoding('UTF-8')
+            txt = txt.encode(l(:general_pdf_encoding), :invalid => :replace,
+                              :undef => :replace, :replace => '?')
+            txt.force_encoding('ASCII-8BIT')
+          else
+            @ic ||= Iconv.new(l(:general_pdf_encoding), 'UTF-8')
+            txt = begin
+              @ic.iconv(txt)
+            rescue
+              txt
+            end || ''
+          end
           # 0x5c char handling
           txt.gsub(/\\/, "\\\\\\\\")
         end