diff --git a/anki/media.py b/anki/media.py
index d44065117..822982050 100644
--- a/anki/media.py
+++ b/anki/media.py
@@ -213,6 +213,7 @@ class MediaManager(object):
             allRefs.update(noteRefs)
         # loop through media folder
         unused = []
+        invalid = []
         if local is None:
             files = os.listdir(mdir)
         else:
@@ -225,6 +226,9 @@ class MediaManager(object):
             if file.startswith("_"):
                 # leading _ says to ignore file
                 continue
+            if not isinstance(file, unicode):
+                invalid.append(unicode(file, sys.getfilesystemencoding(), "replace"))
+                continue
             nfcFile = unicodedata.normalize("NFC", file)
             # we enforce NFC fs encoding on non-macs; on macs we'll have gotten
             # NFD so we use the above variable for comparing references
@@ -242,7 +246,7 @@ class MediaManager(object):
             else:
                 allRefs.discard(nfcFile)
         nohave = [x for x in allRefs if not x.startswith("_")]
-        return (nohave, unused)
+        return (nohave, unused, invalid)
 
     def _normalizeNoteRefs(self, nid):
         note = self.col.getNote(nid)
@@ -336,6 +340,9 @@ class MediaManager(object):
         return re.sub(self._illegalCharReg, "", str)
 
     def hasIllegal(self, str):
+        # a file that couldn't be decoded to unicode is considered invalid
+        if not isinstance(str, unicode):
+            return False
         return not not re.search(self._illegalCharReg, str)
 
     # Media syncing - bundling zip files to send to server
diff --git a/aqt/main.py b/aqt/main.py
index 2b0f840f8..395346e72 100644
--- a/aqt/main.py
+++ b/aqt/main.py
@@ -913,11 +913,16 @@ will be lost. Continue?"""))
 
     def onCheckMediaDB(self):
         self.progress.start(immediate=True)
-        (nohave, unused) = self.col.media.check()
+        (nohave, unused, invalid) = self.col.media.check()
         self.progress.finish()
         # generate report
         report = ""
+        if invalid:
+            report += _("Invalid encoding; please rename:")
+            report += "\n" + "\n".join(invalid)
         if unused:
+            if report:
+                report += "\n\n\n"
             report += _(
                 "In media folder but not used by any cards:")
             report += "\n" + "\n".join(unused)