diff --git a/admin/app/admin/jam_tracks.rb b/admin/app/admin/jam_tracks.rb
index 8e62bbc85..6cfb6c1a3 100644
--- a/admin/app/admin/jam_tracks.rb
+++ b/admin/app/admin/jam_tracks.rb
@@ -26,6 +26,7 @@ ActiveAdmin.register  JamRuby::JamTrack, :as => 'JamTracks' do
     column :id
     column :name
     column :description
+    column :version
     column :initial_play_silence
     column :time_signature
     column :status
diff --git a/admin/app/views/admin/jam_tracks/_form.html.slim b/admin/app/views/admin/jam_tracks/_form.html.slim
index 16e53837d..3950ee86f 100644
--- a/admin/app/views/admin/jam_tracks/_form.html.slim
+++ b/admin/app/views/admin/jam_tracks/_form.html.slim
@@ -7,6 +7,8 @@
         | JamTrack should only be made available (to end users) if all its sub-component are in place:
     = f.input :available, as: :boolean
     = f.input :description, :input_html => { :rows=>5, :maxlength=>1000 }
+    = f.input :plan_code, :label=>'Recurly Plan Code', :required=>true, :hint => 'Must match plan code in Recurly'
+    = f.input :version, :label => 'Version', :hint => 'Increment this value whenever you invalidate (update) the definition of this JamTrack'
     = f.input :initial_play_silence, :label => 'Initial Play Silence (seconds)'
     = f.input :time_signature, collection: JamRuby::JamTrack::TIME_SIGNATURES, include_blank: false
     = f.input :status, collection: JamRuby::JamTrack::STATUS, include_blank: false
@@ -24,7 +26,6 @@
     = f.input :reproduction_royalty_amount, :required=>true, :input_html=>{type:'numeric'}
     = f.input :licensor_royalty_amount, :required=>true, :input_html=>{type:'numeric'}
     = f.input :pro_royalty_amount, :required=>true, :input_html=>{type:'numeric'}
-    = f.input :plan_code, :label=>'Recurly Plan Code', :required=>true
     = f.input :url, :as => :file, :label => 'Audio File'
 
     = f.semantic_fields_for :jam_track_tracks do |track|
diff --git a/db/manifest b/db/manifest
index 55f1373b5..9bb10cf65 100755
--- a/db/manifest
+++ b/db/manifest
@@ -252,4 +252,5 @@ metronome.sql
 recorded_backing_tracks.sql
 recorded_backing_tracks_add_filename.sql
 user_syncs_include_backing_tracks.sql
-remove_bpm_from_jamtracks.sql
\ No newline at end of file
+remove_bpm_from_jamtracks.sql
+jam_track_version.sql
\ No newline at end of file
diff --git a/db/up/jam_track_version.sql b/db/up/jam_track_version.sql
new file mode 100644
index 000000000..7c1efff86
--- /dev/null
+++ b/db/up/jam_track_version.sql
@@ -0,0 +1 @@
+ALTER TABLE jam_tracks ADD COLUMN version VARCHAR NOT NULL DEFAULT 0;
diff --git a/ruby/lib/jam_ruby/jam_tracks_manager.rb b/ruby/lib/jam_ruby/jam_tracks_manager.rb
index a5c04cd61..9618ab3c4 100644
--- a/ruby/lib/jam_ruby/jam_tracks_manager.rb
+++ b/ruby/lib/jam_ruby/jam_tracks_manager.rb
@@ -42,10 +42,11 @@ module JamRuby
           title=jam_track.name          
           output_jkz=File.join(tmp_dir, "#{title.parameterize}.jkz")
           py_file = File.join(py_root, "jkcreate.py")
+          version = jam_track.version
           @@log.info "Executing python source in #{py_file}, outputting to #{tmp_dir} (#{output_jkz})"
           
           # From http://stackoverflow.com/questions/690151/getting-output-of-system-calls-in-ruby/5970819#5970819:
-          cli = "python #{py_file} -D -k #{sku} -p #{tmp_dir}/pkey.pem -s #{tmp_dir}/skey.pem #{jam_file_opts} -o #{output_jkz} -t '#{title}'"
+          cli = "python #{py_file} -D -k #{sku} -p #{tmp_dir}/pkey.pem -s #{tmp_dir}/skey.pem #{jam_file_opts} -o #{output_jkz} -t '#{title}' -V '#{version}'"
           Open3.popen3(cli) do |stdin, stdout, stderr, wait_thr|
             pid = wait_thr.pid
             exit_status = wait_thr.value
diff --git a/ruby/lib/jam_ruby/models/jam_track.rb b/ruby/lib/jam_ruby/models/jam_track.rb
index 3d884ca3a..552b4238b 100644
--- a/ruby/lib/jam_ruby/models/jam_track.rb
+++ b/ruby/lib/jam_ruby/models/jam_track.rb
@@ -16,7 +16,7 @@ module JamRuby
                   :original_artist, :songwriter, :publisher, :licensor, :licensor_id, :pro, :genre, :genre_id, :sales_region, :price,
                   :reproduction_royalty, :public_performance_royalty, :reproduction_royalty_amount,
                   :licensor_royalty_amount, :pro_royalty_amount, :plan_code, :initial_play_silence, :jam_track_tracks_attributes,
-                  :jam_track_tap_ins_attributes, :available, as: :admin
+                  :jam_track_tap_ins_attributes, :available, :version, as: :admin
 
     validates :name,            presence: true, uniqueness: true, length: {maximum: 200}
     validates :description,     length: {maximum: 1000}
@@ -30,6 +30,7 @@ module JamRuby
     validates :sales_region,    inclusion: {in: [nil] + SALES_REGION}
     validates_format_of :price, with: /^\d+\.*\d{0,2}$/
     validates :initial_play_silence,    numericality: true, :allow_nil => true
+    validates :version,         presence: true
 
     validates :reproduction_royalty,                  inclusion: {in: [nil, true, false]}
     validates :public_performance_royalty,            inclusion: {in: [nil, true, false]}
diff --git a/web/app/assets/javascripts/download_jamtrack.js.coffee b/web/app/assets/javascripts/download_jamtrack.js.coffee
index 77fa5aa34..162a1772a 100644
--- a/web/app/assets/javascripts/download_jamtrack.js.coffee
+++ b/web/app/assets/javascripts/download_jamtrack.js.coffee
@@ -51,6 +51,7 @@ context.JK.DownloadJamTrack = class DownloadJamTrack
 
     throw "no JamTrack specified" unless @jamTrack?
     throw "invalid size" if @size != 'large' && @size != 'small'
+    throw "no JamTrack version" unless @jamTrack.version?
 
     @path = []
     @states = {
@@ -342,6 +343,13 @@ context.JK.DownloadJamTrack = class DownloadJamTrack
 
     @logger.debug("DownloadJamTrack: JamTrackGetTrackDetail.key_state: " + @trackDetail.key_state)
 
+    # first check if the version is not the same; if so, invalidate.
+
+    if @jamTrack.version != @trackDetail.version
+      @logger.info("DownloadJamTrack: JamTrack on disk is different version. Invalidating")
+      context.jamClient.InvalidateJamTrack(@jamTrack.id)
+      @trackDetail = context.jamClient.JamTrackGetTrackDetail (@jamTrack.id)
+
     switch @trackDetail.key_state
       when 'pending'
         this.transition(@states.keying)
diff --git a/web/app/views/api_jam_tracks/show.rabl b/web/app/views/api_jam_tracks/show.rabl
index f9ea856db..cab264aa5 100644
--- a/web/app/views/api_jam_tracks/show.rabl
+++ b/web/app/views/api_jam_tracks/show.rabl
@@ -1,6 +1,6 @@
 object @jam_track
 
-attributes :id, :name, :description, :recording_type, :original_artist, :songwriter, :publisher, :sales_region, :price
+attributes :id, :name, :description, :recording_type, :original_artist, :songwriter, :publisher, :sales_region, :price, :version
 
 node :genres do |item|
   [item.genre.description] # XXX: need to return single genre; not array
diff --git a/web/app/views/api_jam_tracks/show_for_client.rabl b/web/app/views/api_jam_tracks/show_for_client.rabl
index 1b2db2fe6..7d2b38851 100644
--- a/web/app/views/api_jam_tracks/show_for_client.rabl
+++ b/web/app/views/api_jam_tracks/show_for_client.rabl
@@ -1,6 +1,6 @@
 object @jam_track
 
-attributes :id, :name, :description, :initial_play_silence, :original_artist
+attributes :id, :name, :description, :initial_play_silence, :original_artist, :version
 
 node :jam_track_right_id do |jam_track|
   jam_track.right_for_user(current_user).id