diff --git a/plugins/Filter/plugin.py b/plugins/Filter/plugin.py
index b1f5137ea..09d66218a 100644
--- a/plugins/Filter/plugin.py
+++ b/plugins/Filter/plugin.py
@@ -196,7 +196,8 @@ class Filter(callbacks.Plugin):
         <hexstring> must be a string of hexadecimal digits.
         """
         try:
-            irc.reply(self._hex_decoder(text.encode('utf8'))[0].decode('utf8'))
+            irc.reply(self._hex_decoder(text.encode('utf8'))[0]
+                    .decode('utf8', 'replace'))
         except TypeError:
             irc.error(_('Invalid input.'))
     unhexlify = wrap(unhexlify, ['text'])
diff --git a/plugins/Filter/test.py b/plugins/Filter/test.py
index 1840a311c..fdea060db 100644
--- a/plugins/Filter/test.py
+++ b/plugins/Filter/test.py
@@ -102,6 +102,7 @@ class FilterTest(ChannelPluginTestCase):
     def testHexlifyUnhexlify(self):
         for s in map(str, range(1000, 1010)):
             self.assertResponse('unhexlify [hexlify %s]' % s, s)
+        self.assertNotError('unhexlify ff')
 
     def testScramble(self):
         s = 'the recalcitrant jamessan tests his scramble function'