diff --git a/lib/redmine_dmsf/webdav/controller.rb b/lib/redmine_dmsf/webdav/controller.rb
index 4d140b1a..dfbfaeea 100644
--- a/lib/redmine_dmsf/webdav/controller.rb
+++ b/lib/redmine_dmsf/webdav/controller.rb
@@ -115,11 +115,11 @@ module RedmineDmsf
               # Don't know when projects are added/removed from the visibility list for this user,
               # so don't cache root.
             elsif (pinfo.length == 1) #This is first level, and as such, project path
-              propfind_key = "PROPFIND/#{resource.resource.project.id}"
+              propfind_key = "PROPFIND/#{resource.resource.project_id}"
             else # We made it all the way to DMSF Data
               if resource.collection?
                 # Only store collections in the cache since responses to files are simple and fast already.
-                propfind_key = "PROPFIND/#{resource.resource.project.id}/#{resource.resource.dmsf_folder_id}"
+                propfind_key = "PROPFIND/#{resource.resource.project_id}/#{resource.resource.folder.id}"
               end
             end
           end
diff --git a/lib/redmine_dmsf/webdav/dmsf_resource.rb b/lib/redmine_dmsf/webdav/dmsf_resource.rb
index 64e67b80..46d4163d 100644
--- a/lib/redmine_dmsf/webdav/dmsf_resource.rb
+++ b/lib/redmine_dmsf/webdav/dmsf_resource.rb
@@ -632,6 +632,10 @@ module RedmineDmsf
         end
       end
 
+      def project_id
+        self.project.id if self.project
+      end
+
       private
       # Prepare file for download using Rack functionality:
       # Download (see RedmineDmsf::Webdav::Download) extends Rack::File to allow single-file
diff --git a/lib/redmine_dmsf/webdav/project_resource.rb b/lib/redmine_dmsf/webdav/project_resource.rb
index 932d7ca3..5aeebcd9 100644
--- a/lib/redmine_dmsf/webdav/project_resource.rb
+++ b/lib/redmine_dmsf/webdav/project_resource.rb
@@ -100,10 +100,15 @@ module RedmineDmsf
       def folder
         nil
       end
+
       def file
         nil
       end
 
+      def project_id
+	self.project.id if self.project
+      end
+
     end
   end
 end