diff --git a/lib/rdoc/markup/attr_span.rb b/lib/rdoc/markup/attr_span.rb
index 6fe939fe7d..20ef11cd6d 100644
--- a/lib/rdoc/markup/attr_span.rb
+++ b/lib/rdoc/markup/attr_span.rb
@@ -17,7 +17,7 @@ class RDoc::Markup::AttrSpan
   def set_attrs(start, length, bits)
     updated = false
     for i in start ... (start+length)
-      if (@exclusive & @attrs[i]) == 0
+      if (@exclusive & @attrs[i]) == 0 || (@exclusive & bits) != 0
         @attrs[i] |= bits
         updated = true
       end
diff --git a/lib/rdoc/markup/attribute_manager.rb b/lib/rdoc/markup/attribute_manager.rb
index 2de8a7c9ee..50764510f3 100644
--- a/lib/rdoc/markup/attribute_manager.rb
+++ b/lib/rdoc/markup/attribute_manager.rb
@@ -75,13 +75,13 @@ class RDoc::Markup::AttributeManager
     @exclusive_bitmap = 0
     @attributes = RDoc::Markup::Attributes.new
 
-    add_word_pair "*", "*", :BOLD
-    add_word_pair "_", "_", :EM
+    add_word_pair "*", "*", :BOLD, true
+    add_word_pair "_", "_", :EM, true
     add_word_pair "+", "+", :TT, true
 
-    add_html "em", :EM
-    add_html "i",  :EM
-    add_html "b",  :BOLD
+    add_html "em", :EM, true
+    add_html "i",  :EM, true
+    add_html "b",  :BOLD, true
     add_html "tt",   :TT, true
     add_html "code", :TT, true
   end
diff --git a/test/rdoc/test_rdoc_markup_attribute_manager.rb b/test/rdoc/test_rdoc_markup_attribute_manager.rb
index 2ec135dca7..944364ba89 100644
--- a/test/rdoc/test_rdoc_markup_attribute_manager.rb
+++ b/test/rdoc/test_rdoc_markup_attribute_manager.rb
@@ -250,6 +250,7 @@ class TestRDocMarkupAttributeManager < RDoc::TestCase
     assert_equal '<CODE>aaa</CODE>[:symbol]', output('+aaa+[:symbol]')
     assert_equal '<CODE>aaa[:symbol]</CODE>', output('+aaa[:symbol]+')
     assert_equal 'aaa[:symbol]', output('aaa[:symbol]')
+    assert_equal '<B><CODE>index</CODE></B>', output('<b><tt>index</tt></b>')
   end
 
   def test_exclude_tag_flow