diff --git a/_plugins/details.rb b/_plugins/details.rb
index 8388ea192..3675e7faf 100644
--- a/_plugins/details.rb
+++ b/_plugins/details.rb
@@ -1,5 +1,8 @@
 module Jekyll
   class DetailsTag < Liquid::Block
+
+    @@ids = Hash.new(0)
+
     def initialize(tag_name, block_options, liquid_options)
       super
       @expand = ''
@@ -9,7 +12,10 @@ def initialize(tag_name, block_options, liquid_options)
         @expand = 'expand'
       end
       @title = @options.join(" ")
+
       @id = @options.join("-").downcase
+      @@ids[@id] += 1
+      @id += "-#{@@ids[@id]}" if @@ids[@id] > 1
     end
 
     def render(context)