diff --git a/README.md b/README.md
index 14acddbd0..5cf082a7c 100644
--- a/README.md
+++ b/README.md
@@ -47,8 +47,8 @@ which means you can modify it, redistribute it or use it however you like.
                              %(extractor)s for the provider (youtube, metacafe,
                              etc), %(id)s for the video id and %% for a literal
                              percent. Use - to output to stdout.
-    --restrict-filenames     Avoid some characters such as "&" and spaces in
-                             filenames
+    --restrict-filenames     Restrict filenames to only ASCII characters, and
+                             avoid "&" and spaces in filenames
     -a, --batch-file FILE    file containing URLs to download ('-' for stdin)
     -w, --no-overwrites      do not overwrite files
     -c, --continue           resume partially downloaded files
diff --git a/test/test_utils.py b/test/test_utils.py
index 0a435ddc5..0b57e016c 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -22,10 +22,10 @@ class TestUtil(unittest.TestCase):
 
 		self.assertEqual(sanitize_filename(u'123'), u'123')
 
-		self.assertEqual(u'abc-de', sanitize_filename(u'abc/de'))
+		self.assertEqual(u'abc_de', sanitize_filename(u'abc/de'))
 		self.assertFalse(u'/' in sanitize_filename(u'abc/de///'))
 
-		self.assertEqual(u'abc-de', sanitize_filename(u'abc/<>\\*|de'))
+		self.assertEqual(u'abc_de', sanitize_filename(u'abc/<>\\*|de'))
 		self.assertEqual(u'xxx', sanitize_filename(u'xxx/<>\\*|'))
 		self.assertEqual(u'yes no', sanitize_filename(u'yes? no'))
 		self.assertEqual(u'this - that', sanitize_filename(u'this: that'))
@@ -45,14 +45,17 @@ class TestUtil(unittest.TestCase):
 
 		self.assertEqual(sanitize_filename(u'123', restricted=True), u'123')
 
-		self.assertEqual(u'abc-de', sanitize_filename(u'abc/de', restricted=True))
+		self.assertEqual(u'abc_de', sanitize_filename(u'abc/de', restricted=True))
 		self.assertFalse(u'/' in sanitize_filename(u'abc/de///', restricted=True))
 
-		self.assertEqual(u'abc-de', sanitize_filename(u'abc/<>\\*|de', restricted=True))
+		self.assertEqual(u'abc_de', sanitize_filename(u'abc/<>\\*|de', restricted=True))
 		self.assertEqual(u'xxx', sanitize_filename(u'xxx/<>\\*|', restricted=True))
 		self.assertEqual(u'yes_no', sanitize_filename(u'yes? no', restricted=True))
 		self.assertEqual(u'this_-_that', sanitize_filename(u'this: that', restricted=True))
 
+		self.assertEqual(sanitize_filename(u'aäb', restricted=True), u'a_b')
+		self.assertTrue(sanitize_filename(u'ö', restricted=True) != u'') # No empty filename
+
 		forbidden = u'"\0\\/&: \'\t\n'
 		for fc in forbidden:
 			print('input: ' + fc + ', result: ' + repr(sanitize_filename(fc, restricted=True)))
diff --git a/youtube-dl.1 b/youtube-dl.1
index 64120a8d2..ae303b672 100644
--- a/youtube-dl.1
+++ b/youtube-dl.1
@@ -59,8 +59,8 @@ redistribute it or use it however you like.
 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ %(extractor)s\ for\ the\ provider\ (youtube,\ metacafe,
 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ etc),\ %(id)s\ for\ the\ video\ id\ and\ %%\ for\ a\ literal
 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ percent.\ Use\ -\ to\ output\ to\ stdout.
---restrict-filenames\ \ \ \ \ Avoid\ some\ characters\ such\ as\ "&"\ and\ spaces\ in
-\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ filenames
+--restrict-filenames\ \ \ \ \ Restrict\ filenames\ to\ only\ ASCII\ characters,\ and
+\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ avoid\ "&"\ and\ spaces\ in\ filenames
 -a,\ --batch-file\ FILE\ \ \ \ file\ containing\ URLs\ to\ download\ (\[aq]-\[aq]\ for\ stdin)
 -w,\ --no-overwrites\ \ \ \ \ \ do\ not\ overwrite\ files
 -c,\ --continue\ \ \ \ \ \ \ \ \ \ \ resume\ partially\ downloaded\ files
diff --git a/youtube_dl/__init__.py b/youtube_dl/__init__.py
index cbf1dd1a7..c3e0f78e5 100644
--- a/youtube_dl/__init__.py
+++ b/youtube_dl/__init__.py
@@ -274,7 +274,7 @@ def parseOpts():
 			dest='outtmpl', metavar='TEMPLATE', help='output filename template. Use %(title)s to get the title, %(uploader)s for the uploader name, %(autonumber)s to get an automatically incremented number, %(ext)s for the filename extension, %(upload_date)s for the upload date (YYYYMMDD), %(extractor)s for the provider (youtube, metacafe, etc), %(id)s for the video id and %% for a literal percent. Use - to output to stdout.')
 	filesystem.add_option('--restrict-filenames',
 			action='store_true', dest='restrictfilenames',
-			help='Avoid some characters such as "&" and spaces in filenames', default=False)
+			help='Restrict filenames to only ASCII characters, and avoid "&" and spaces in filenames', default=False)
 	filesystem.add_option('-a', '--batch-file',
 			dest='batchfile', metavar='FILE', help='file containing URLs to download (\'-\' for stdin)')
 	filesystem.add_option('-w', '--no-overwrites',
diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 1f60d34ae..3339f56ec 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -207,15 +207,20 @@ def sanitize_filename(s, restricted=False):
 		elif char == ':':
 			return '_-' if restricted else ' -'
 		elif char in '\\/|*<>':
-			return '-'
+			return '_'
 		if restricted and (char in '&\'' or char.isspace()):
 			return '_'
+		if restricted and ord(char) > 127:
+			return '_'
 		return char
 
 	result = u''.join(map(replace_insane, s))
-	while '--' in result:
-		result = result.replace('--', '-')
-	return result.strip('-')
+	while '__' in result:
+		result = result.replace('__', '_')
+	result = result.strip('_')
+	if not result:
+		result = '_'
+	return result
 
 def orderedSet(iterable):
 	""" Remove all duplicates from the input iterable """