diff --git a/python/GafferImageTest/CatalogueTest.py b/python/GafferImageTest/CatalogueTest.py
index 01c791d0ac2..a1059b2bda1 100644
--- a/python/GafferImageTest/CatalogueTest.py
+++ b/python/GafferImageTest/CatalogueTest.py
@@ -41,6 +41,7 @@
 import imath
 import pathlib
 import unittest
+import subprocess
 
 import IECore
 
@@ -615,13 +616,15 @@ def testDeleteBeforeSaveCompletesWithScriptVariables( self ) :
 
 		self.assertEqual( len( list( baseDirectory.glob( "*" ) ) ), 0 )
 
-	@unittest.skipIf( os.name == "nt", "Windows allows new files in read-only directories" )
 	def testNonWritableDirectory( self ) :
 
 		s = Gaffer.ScriptNode()
 		s["c"] = GafferImage.Catalogue()
 		s["c"]["directory"].setValue( self.temporaryDirectory() / "catalogue" )
-		os.chmod( self.temporaryDirectory(), stat.S_IREAD )
+		if os.name != "nt" :
+			os.chmod( self.temporaryDirectory(), stat.S_IREAD )
+		else :
+			subprocess.check_call( [ "icacls", self.temporaryDirectory(), "/deny", "Users:(OI)(CI)(W)" ] )
 
 		r = GafferImage.ImageReader()
 		r["fileName"].setValue( self.imagesPath() / "blurRange.exr" )
@@ -637,9 +640,17 @@ def testNonWritableDirectory( self ) :
 
 		self.assertEqual( len( mh.messages ), 1 )
 		self.assertEqual( mh.messages[0].level, IECore.Msg.Level.Error )
-		self.assertIn( "Permission denied", mh.messages[0].message )
+		self.assertIn(
+			"Permission denied" if os.name != "nt" else "Access is denied",
+			mh.messages[0].message
+		)
 
-		with self.assertRaisesRegex( RuntimeError, r".* : Could not open \".*\" \(Permission denied\)" ) :
+		with self.assertRaisesRegex(
+			RuntimeError,
+			r".* : Could not open \".*\" " + (
+				"\(Permission denied\)" if os.name != "nt" else "\(No such file or directory\)"
+			)
+		) :
 			GafferImage.ImageAlgo.image( s["c"]["out"] )
 
 	def testDeleteKeepsOrder( self ) :
diff --git a/python/GafferTest/TestCase.py b/python/GafferTest/TestCase.py
index 9ef5ee2d15e..ad0d93261df 100644
--- a/python/GafferTest/TestCase.py
+++ b/python/GafferTest/TestCase.py
@@ -114,11 +114,14 @@ def tearDown( self ) :
 		## \todo Fix Cortex so that wrapped classes don't require garbage collection.
 		IECore.RefCounted.collectGarbage()
 
-		for root, dirs, files in os.walk( self.temporaryDirectory() ) :
-			for fileName in [ p for p in files + dirs if not ( pathlib.Path( root ) / p ).is_symlink() ] :
-				( pathlib.Path( root ) / fileName ).chmod( stat.S_IRWXU )
-
 		if self.__temporaryDirectory is not None :
+			if os.name == "nt" :
+				subprocess.check_call( [ "icacls", self.__temporaryDirectory, "/grant", "Users:(OI)(CI)(W)" ] )
+
+			for root, dirs, files in os.walk( self.__temporaryDirectory ) :
+				for fileName in [ p for p in files + dirs if not ( pathlib.Path( root ) / p ).is_symlink() ] :
+					( pathlib.Path( root ) / fileName ).chmod( stat.S_IRWXU )
+
 			shutil.rmtree( self.__temporaryDirectory )
 
 		IECore.MessageHandler.setDefaultHandler( self.__defaultMessageHandler )
diff --git a/python/GafferUSDTest/USDLayerWriterTest.py b/python/GafferUSDTest/USDLayerWriterTest.py
index 73a81290ff8..43eb6913a6b 100644
--- a/python/GafferUSDTest/USDLayerWriterTest.py
+++ b/python/GafferUSDTest/USDLayerWriterTest.py
@@ -265,8 +265,5 @@ def testNoWritePermissions( self ) :
 		with self.assertRaisesRegex( RuntimeError, 'Failed to export layer to "{}"'.format( layerWriter["fileName"].getValue() ) ) :
 			layerWriter["task"].execute()
 
-		if os.name == "nt" :
-			subprocess.check_call( [ "icacls", self.temporaryDirectory(), "/grant", "Users:(OI)(CI)(W)" ] )
-
 if __name__ == "__main__":
 	unittest.main()