diff --git a/app/models/dmsf_file.rb b/app/models/dmsf_file.rb
index a38533f4..2a04cc2d 100644
--- a/app/models/dmsf_file.rb
+++ b/app/models/dmsf_file.rb
@@ -464,8 +464,12 @@ class DmsfFile < ActiveRecord::Base
     last_revision && Redmine::MimeType.is_type?('video', last_revision.disk_filename)
   end
 
+  def html?
+    last_revision && (Redmine::MimeType.of(last_revision.disk_filename) == 'text/html')
+  end
+
   def disposition
-    (image? || pdf? || video?) ? 'inline' : 'attachment'
+    (image? || pdf? || video? || html?) ? 'inline' : 'attachment'
   end
 
   def preview(limit)
diff --git a/test/unit/dmsf_file_test.rb b/test/unit/dmsf_file_test.rb
index 74ba252b..26daac94 100644
--- a/test/unit/dmsf_file_test.rb
+++ b/test/unit/dmsf_file_test.rb
@@ -195,6 +195,9 @@ class DmsfFileTest < RedmineDmsf::Test::UnitTest
     # Video
     @file1.last_revision.disk_filename = 'test.mp4'
     assert_equal 'inline', @file1.disposition
+    # HTML
+    @file1.last_revision.disk_filename = 'test.html'
+    assert_equal 'inline', @file1.disposition
   end
 
   def test_image
@@ -221,6 +224,12 @@ class DmsfFileTest < RedmineDmsf::Test::UnitTest
     assert @file1.video?
   end
 
+  def test_html
+    assert !@file1.html?
+    @file1.last_revision.disk_filename = 'test.html'
+    assert @file1.html?
+  end
+
   def test_findn_file_by_name
     assert DmsfFile.find_file_by_name(@project1, nil, 'test.txt')
     assert_nil DmsfFile.find_file_by_name(@project1, nil, 'test.odt')