diff --git a/Lib/fontTools/ufoLib/__init__.py b/Lib/fontTools/ufoLib/__init__.py
index 70ec6f8a8..26b7ddd3e 100755
--- a/Lib/fontTools/ufoLib/__init__.py
+++ b/Lib/fontTools/ufoLib/__init__.py
@@ -175,7 +175,7 @@ class _UFOBaseIO(object):
 				)
 			if self.fs.exists(fileName) and data == self.fs.readbytes(fileName):
 				return
-			self.fs.setbytes(fileName, data)
+			self.fs.writebytes(fileName, data)
 		else:
 			with self.fs.openbin(fileName, mode="w") as fp:
 				try:
@@ -1009,12 +1009,12 @@ class UFOWriter(UFOReader):
 			if self.fs.isfile(path) and data == self.fs.readbytes(path):
 				return
 		try:
-			self.fs.setbytes(path, data)
+			self.fs.writebytes(path, data)
 		except fs.errors.FileExpected:
 			raise UFOLibError("A directory exists at '%s'" % path)
 		except fs.errors.ResourceNotFound:
 			self.fs.makedirs(fs.path.dirname(path), recreate=True)
-			self.fs.setbytes(path, data)
+			self.fs.writebytes(path, data)
 
 	def getFileObjectForPath(self, path, mode="w", encoding=None):
 		"""
diff --git a/Lib/fontTools/ufoLib/glifLib.py b/Lib/fontTools/ufoLib/glifLib.py
index 1f7aaf435..bcdc60f91 100755
--- a/Lib/fontTools/ufoLib/glifLib.py
+++ b/Lib/fontTools/ufoLib/glifLib.py
@@ -423,7 +423,7 @@ class GlyphSet(_UFOBaseIO):
 			and data == self.fs.readbytes(fileName)
 		):
 			return
-		self.fs.setbytes(fileName, data)
+		self.fs.writebytes(fileName, data)
 
 	def deleteGlyph(self, glyphName):
 		"""Permanently delete the glyph from the glyph set on disk. Will