diff --git a/lib/redmine_dmsf/webdav/base_resource.rb b/lib/redmine_dmsf/webdav/base_resource.rb
index 3f1ff69b..517ad763 100644
--- a/lib/redmine_dmsf/webdav/base_resource.rb
+++ b/lib/redmine_dmsf/webdav/base_resource.rb
@@ -60,8 +60,8 @@ module RedmineDmsf
         @public_path.force_encoding('utf-8')
       end
 
-      # Generate HTML for Get requests
-      def html_display
+      # Generate HTML for Get requests, or Head requests if no_body is true
+      def html_display(no_body = false)
         @response.body = ''
         Confict unless collection?        
         entities = children.map{|child| 
@@ -80,7 +80,7 @@ module RedmineDmsf
           '',
           '',
         ] + entities if parent        
-        @response.body << index_page % [ path.empty? ? '/' : path, path.empty? ? '/' : path, entities ]
+        @response.body << index_page % [ path.empty? ? '/' : path, path.empty? ? '/' : path, entities ] unless no_body
       end
 
       # Run method through proxy class - ensuring always compatible child is generated      
@@ -170,4 +170,4 @@ module RedmineDmsf
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/redmine_dmsf/webdav/controller.rb b/lib/redmine_dmsf/webdav/controller.rb
index 26a07b13..9d52032c 100644
--- a/lib/redmine_dmsf/webdav/controller.rb
+++ b/lib/redmine_dmsf/webdav/controller.rb
@@ -26,6 +26,20 @@ module RedmineDmsf
     class Controller < DAV4Rack::Controller
       include DAV4Rack::Utils
 
+      # Return response to OPTIONS
+      def options
+        # Always return MethodNotAllowed(405) because how MsOffice uses anonymous OPTIONS request.
+        # See https://support.microsoft.com/en-us/kb/2019105
+        MethodNotAllowed
+      end
+
+      # Return response to HEAD
+      def head
+        # Don't check resource.exist? because it returns false for anonymous requests and MsOffice's uses anonymous HEAD requests.
+        # See https://support.microsoft.com/en-us/kb/2019105
+        resource.head(request, response)
+      end
+
       # Return response to PROPFIND
       def propfind
         unless(resource.exist?)
diff --git a/lib/redmine_dmsf/webdav/dmsf_resource.rb b/lib/redmine_dmsf/webdav/dmsf_resource.rb
index cf3c5e37..f12dde95 100644
--- a/lib/redmine_dmsf/webdav/dmsf_resource.rb
+++ b/lib/redmine_dmsf/webdav/dmsf_resource.rb
@@ -194,6 +194,22 @@ module RedmineDmsf
         OK
       end
 
+      # Process incoming HEAD request
+      #
+      # MsOFfice uses anonymous HEAD requests, so always return a response.
+      # See https://support.microsoft.com/en-us/kb/2019105
+      ##
+      def head(request, response)
+        raise NotFound unless project && project.module_enabled?('dmsf') && (folder || file)
+        if collection?
+          html_display(true)
+          response['Content-Length'] = response.body.bytesize.to_s
+        else
+          response.body = ''
+        end
+        OK
+      end
+
       # Process incoming MKCOL request
       #
       # Create a DmsfFolder at location requested, only if parent is a folder (or root)
diff --git a/lib/redmine_dmsf/webdav/index_resource.rb b/lib/redmine_dmsf/webdav/index_resource.rb
index bc39e8b4..0acf48e0 100644
--- a/lib/redmine_dmsf/webdav/index_resource.rb
+++ b/lib/redmine_dmsf/webdav/index_resource.rb
@@ -68,6 +68,12 @@ module RedmineDmsf
         4096
       end
 
+      def head(request, response)
+        html_display(true)
+        response['Content-Length'] = response.body.bytesize.to_s
+        OK
+      end
+
       def get(request, response)
         html_display
         response['Content-Length'] = response.body.bytesize.to_s
diff --git a/lib/redmine_dmsf/webdav/project_resource.rb b/lib/redmine_dmsf/webdav/project_resource.rb
index 459f0d96..36a9588b 100644
--- a/lib/redmine_dmsf/webdav/project_resource.rb
+++ b/lib/redmine_dmsf/webdav/project_resource.rb
@@ -80,6 +80,12 @@ module RedmineDmsf
         4096
       end
 
+      def head(request, response)
+        html_display(true)
+        response['Content-Length'] = response.body.bytesize.to_s
+        OK        
+      end
+
       def get(request, response)
         html_display
         response['Content-Length'] = response.body.bytesize.to_s
@@ -95,4 +101,4 @@ module RedmineDmsf
 
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/redmine_dmsf/webdav/resource_proxy.rb b/lib/redmine_dmsf/webdav/resource_proxy.rb
index 15b933d4..782ff67d 100644
--- a/lib/redmine_dmsf/webdav/resource_proxy.rb
+++ b/lib/redmine_dmsf/webdav/resource_proxy.rb
@@ -51,7 +51,10 @@ module RedmineDmsf
         # going to fork it to ensure compliance, checking the request method in the authentication
         # seems the next best step, if the request method is OPTIONS return true, controller will simply
         # call the options method within, which accesses nothing, just returns headers about dav env.
-        return true if @request.request_method.downcase == 'options' && (path == '/' || path.empty?)
+        #return true if @request.request_method.downcase == 'options' && (path == '/' || path.empty?)
+        # MsOffice does anonymous OPTIONS and HEAD requests.
+        return true if @request.request_method.downcase == 'options'
+        return true if @request.request_method.downcase == 'head'
         return false unless username && password
         User.current = User.try_to_login(username, password)
         return User.current && !User.current.anonymous?
@@ -97,6 +100,10 @@ module RedmineDmsf
         @resource_c.content_length
       end
 
+      def head(request,response)
+        @resource_c.head(request, response)
+      end
+
       def get(request, response)
         @resource_c.get(request, response)
       end