diff --git a/manifest/sourcefile.py b/manifest/sourcefile.py
index 4c37765..499518b 100644
--- a/manifest/sourcefile.py
+++ b/manifest/sourcefile.py
@@ -16,7 +16,7 @@
 
 wd_pattern = "*.py"
 
-reference_file_re = re.compile(r'-(not)?ref[0-9]*(-|$)')
+reference_file_re = re.compile(r'(^|[\-_])(not)?ref[0-9]*([\-_]|$)')
 
 def replace_end(s, old, new):
     """
diff --git a/manifest/tests/test_sourcefile.py b/manifest/tests/test_sourcefile.py
index 7096f06..a1625f6 100644
--- a/manifest/tests/test_sourcefile.py
+++ b/manifest/tests/test_sourcefile.py
@@ -96,7 +96,10 @@ def test_name_is_visual(rel_path):
     "css21/css-e-notation-ref-1.html",
     "css21/floats/floats-placement-vertical-004-ref2.xht",
     "css21/box/rtl-linebreak-notref1.xht",
-    "css21/box/rtl-linebreak-notref2.xht"
+    "css21/box/rtl-linebreak-notref2.xht",
+    "2dcontext/drawing-images-to-the-canvas/drawimage_html_image_5_ref.html",
+    "2dcontext/line-styles/lineto_ref.html",
+    "html/rendering/non-replaced-elements/the-fieldset-element-0/ref.html"
 ])
 def test_name_is_reference(rel_path):
     s = create(rel_path)