diff --git a/app/controllers/versions_controller.rb b/app/controllers/versions_controller.rb
index bc3852f..b8056ec 100644
--- a/app/controllers/versions_controller.rb
+++ b/app/controllers/versions_controller.rb
@@ -146,7 +146,7 @@ class VersionsController < ApplicationController
   end
 
   def destroy
-    if @version.fixed_issues.empty?
+    if @version.fixed_issues.empty? and !@version.referenced_by_a_custom_field?
       @version.destroy
       respond_to do |format|
         format.html { redirect_back_or_default settings_project_path(@project, :tab => 'versions') }
diff --git a/app/models/version.rb b/app/models/version.rb
index ed5b628..3df4caa 100644
--- a/app/models/version.rb
+++ b/app/models/version.rb
@@ -168,6 +168,13 @@ class Version < ActiveRecord::Base
     @closed_issues_count
   end
 
+  def referenced_by_a_custom_field?
+    !CustomValue.where("custom_field_id IN (SELECT id
+                                            FROM #{CustomField.table_name}
+                                            WHERE field_format='version')
+                        AND value = ?", id).empty?
+  end
+
   def wiki_page
     if project.wiki && !wiki_page_title.blank?
       @wiki_page ||= project.wiki.find_page(wiki_page_title)