diff --git a/lib/url_generator.rb b/lib/url_generator.rb
index 3d2f38f1..d574f7f4 100644
--- a/lib/url_generator.rb
+++ b/lib/url_generator.rb
@@ -87,6 +87,7 @@ class UrlGenerator < AbstractUrlGenerator
   end
 
   def page_link(mode, name, text, web_address, known_page)
+    return %{<span class='wikilink-error'><b>Illegal link (contains a '.'):</b> [[#{text}]]</span>} if text.include?('.')
     case mode
     when :export
       if known_page 
diff --git a/public/stylesheets/instiki.css b/public/stylesheets/instiki.css
index 5be36371..39457c10 100644
--- a/public/stylesheets/instiki.css
+++ b/public/stylesheets/instiki.css
@@ -393,6 +393,16 @@ margin:0;
 padding:0;
 }
 
+span.wikilink-error {
+ border: solid 2px red;
+ background-color: pink;
+}
+
+span.wikilink-error b {
+ font-size: 80%;
+ color: #009;
+}
+
 merror {display:inline;font-size:1em;}
 math[display=block] {overflow:auto;}
 math { white-space: nowrap }
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 383b5bf1..76302762 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -127,6 +127,7 @@ class StubUrlGenerator < AbstractUrlGenerator
 
   def page_link(mode, name, text, web_address, known_page)
     link = CGI.escape(name)
+    return %{<span class='wikilink-error'><b>Illegal link (contains a '.'):</b> [[#{text}]]</span>} if text.include?('.')
     case mode
     when :export
       if known_page then %{<a class="existingWikiWord" href="#{link}.html">#{text}</a>}
diff --git a/test/unit/page_test.rb b/test/unit/page_test.rb
index 92fbbc91..3011e21f 100644
--- a/test/unit/page_test.rb
+++ b/test/unit/page_test.rb
@@ -127,7 +127,7 @@ class PageTest < ActiveSupport::TestCase
   def test_revise_changes_references_from_wanted_to_linked_for_redirected_pages
     web = Web.find(1)
     new_page = Page.new(:web => web, :name => 'NewPage')
-    new_page.revise('Reference to HappyPage, and to WantedPage2', 'NewPage', Time.now, 'AlexeyVerkhovsky', 
+    new_page.revise('Reference to HappyPage, and to WantedPage2', 'NewPage', Time.local(2004, 4, 5, 17, 56), 'AlexeyVerkhovsky', 
         test_renderer)
     
     references = new_page.wiki_references(true)
@@ -156,15 +156,21 @@ class PageTest < ActiveSupport::TestCase
     assert_equal 'WantedPage2', references[1].referenced_name
     assert_equal WikiReference::WANTED_PAGE, references[1].link_type
     
-    new_page.revise('Reference to HappyPage', 'NewPage', Time.now, 'AlexeyVerkhovsky', 
+    new_page.revise('Reference to HappyPage and to WantedPage2.pdf and [[foo.pdf]]', 'NewPage', Time.now, 'AlexeyVerkhovsky', 
         test_renderer)
     references = new_page.wiki_references(true)
-    assert_match( "Reference to <a class='existingWikiWord' href='\.\./show/MyPage'>Happy Page</a>",
+    assert_equal( "<p>Reference to <a class='existingWikiWord' href='\.\./show/MyPage'>Happy Page</a>" +
+      " and to <span class='newWikiWord'>Wanted Page2<a href='../show/WantedPage2'>?</a></span>.pdf " +
+      "and <span class='wikilink-error'><b>Illegal link (contains a &#39;.&#39;):</b> [[foo.pdf]]</span></p>",
          test_renderer(new_page.revisions.last).display_content(true) )
-    assert_equal 1, references.size
+    assert_equal 3, references.size
 #   now it works.
     assert_equal 'HappyPage', references[0].referenced_name
     assert_equal WikiReference::LINKED_PAGE, references[0].link_type
+    assert_equal 'WantedPage2', references[1].referenced_name
+    assert_equal WikiReference::WANTED_PAGE, references[1].link_type
+    assert_equal 'foo.pdf', references[2].referenced_name
+    assert_equal WikiReference::WANTED_PAGE, references[1].link_type
   end
 
   def test_rollback