diff --git a/__init__.py b/__init__.py
index f2582e8..2170be4 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,5 +1,6 @@
 
 from . import bencode
+from functools import reduce
 from hashlib import sha1
 import importlib.resources
 import itertools
@@ -19,9 +20,22 @@ class Storage:
 
 		self._buildindex()
 
+	def _filepaths(self):
+		for curfile in self._files:
+			fname = pathlib.Path(
+			    *(x.decode(self._encoding) for x in
+			    curfile['path']))
+			curfilepath = self._rootpath / fname
+
+			yield curfile, fname, curfilepath
+
+	def allfiles(self):
+		for x, y, curfilepath in self._filepaths():
+			yield curfilepath
+
 	def _buildindex(self):
 		self._index = []
-		files = iter(self._files)
+		files = self._filepaths()
 		left = 0
 		curfile = None
 
@@ -29,11 +43,7 @@ class Storage:
 			if curfile is None or curfileoff == curfile['length']:
 				# next file
 				try:
-					curfile = next(files)
-					fname = pathlib.Path(
-					    *(x.decode(self._encoding) for x in
-					    curfile['path']))
-					curfilepath = self._rootpath / fname
+					curfile, fname, curfilepath = next(files)
 				except StopIteration:
 					break
 				curfileoff = 0
@@ -51,6 +61,10 @@ class Storage:
 			curfileoff += sz
 			left -= sz
 
+	def filesforpiece(self, idx):
+		for x in self._index[idx]:
+			yield x['file']
+
 	def apply_piece(self, idx, fun):
 		for i in self._index[idx]:
 			with open(i['file'], 'rb') as fp:
@@ -72,14 +86,28 @@ def validate(torrent, basedir):
 	stor = Storage(torrentdir, info['files'], info['piece length'], encoding)
 
 	pieces = info['pieces']
+	piecescnt = len(pieces) // 20
+	valid = [ None ] * piecescnt
 	for num, i in enumerate(pieces[x:x+20] for x in range(0, len(pieces),
 	    20)):
 		hash = sha1()
 
 		stor.apply_piece(num, hash.update)
 
-		if hash.digest() != i:
-			raise ValueError
+		if hash.digest() == i:
+			valid[num] = True
+		else:
+			valid[num] = False
+
+	# if any piece of a file is bad, it's bad
+	allfiles = set(stor.allfiles())
+
+	badpieces = [ x for x, v in enumerate(valid) if not v ]
+
+	badfiles = reduce(set.__or__, (set(stor.filesforpiece(x)) for x in
+	    badpieces), set())
+
+	return allfiles - badfiles, badfiles
 
 class _TestCases(unittest.TestCase):
 	dirname = 'somedir'
@@ -155,13 +183,20 @@ class _TestCases(unittest.TestCase):
 
 		missingfiles = self.origfiledata.copy()
 
-		missingfiles['filea.txt'] = b''
-		missingfiles['filec.txt'] = b'\x00\x00\x00\x00a\n'
-		missingfiles['filee.txt'] = b'no'
+		badfiles = {
+			'filea.txt': b'',
+			'filec.txt': b'\x00\x00\x00\x00a\n',
+			'filee.txt': b'no',
+		}
+
+		missingfiles.update(badfiles)
 
 		sd = self.basetempdir / self.dirname
 		sd.mkdir()
 
 		self.make_files(sd, missingfiles)
 
-		self.assertRaises(ValueError, validate, self.torrent, self.basetempdir)
+		val, inval = validate(self.torrent, self.basetempdir)
+
+		self.assertEqual(set(val), { sd / x for x in missingfiles.keys() if x not in badfiles })
+		self.assertEqual(set(inval), { sd / x for x in badfiles.keys() })