diff --git a/app/models/dmsf_file.rb b/app/models/dmsf_file.rb
index ee890a44..537e8466 100644
--- a/app/models/dmsf_file.rb
+++ b/app/models/dmsf_file.rb
@@ -488,6 +488,10 @@ class DmsfFile < ActiveRecord::Base
     (image? || pdf? || video? || html?) ? 'inline' : 'attachment'
   end
 
+  def thumbnailable?
+    image? && Redmine::Thumbnail.convert_available?
+  end
+
   def preview(limit)
     result = +'No preview available'
     if text?
diff --git a/app/views/dmsf_files/_thumbnails.html.erb b/app/views/dmsf_files/_thumbnails.html.erb
index 13763564..ca8e0a71 100644
--- a/app/views/dmsf_files/_thumbnails.html.erb
+++ b/app/views/dmsf_files/_thumbnails.html.erb
@@ -22,7 +22,7 @@
 
 <% # Thumbnails %>
 <% if defined?(thumbnails) && thumbnails %>
-    <% images = links.map{ |x| x[0] }.select(&:image?) %>
+    <% images = links.map{ |x| x[0] }.select(&:thumbnailable?) %>
     <% if images.any? %>
         <% if link_to # Redmine classic %>
           <div class="thumbnails">