Index: app/views/journals/diff.html.erb
===================================================================
--- app/views/journals/diff.html.erb	(revision 4954)
+++ app/views/journals/diff.html.erb	(working copy)
@@ -5,6 +5,6 @@
 <%= simple_format_without_paragraph @diff.to_html %>
 </div>
 
-<p><%= link_to l(:button_back), issue_path(@issue), :onclick => 'history.back(); return false;' %></p>
+<p><%= link_to l(:button_back), issue_path(@issue), :onclick => 'if (history.length>1){history.back(); return false;}' %></p>
 
 <% html_title "#{@issue.tracker.name} ##{@issue.id}: #{@issue.subject}" %>