--- trac/mimeview/api.py.orig	2009-02-10 18:51:16.255851515 +0000
+++ trac/mimeview/api.py	2009-02-10 18:51:19.245896616 +0000
@@ -421,7 +421,7 @@ def is_binary(data):
     """
     if isinstance(data, str) and detect_unicode(data):
         return False
-    return '\0' in data[:1000]
+    return ('\0' in data[:1000]) or data.startswith('%PDF-')
 
 def detect_unicode(data):
     """Detect different unicode charsets by looking for BOMs (Byte Order Marks).