diff --git a/Lib/test/test_compileall.py b/Lib/test/test_compileall.py
index d1c9ee5..866eb40 100644
--- a/Lib/test/test_compileall.py
+++ b/Lib/test/test_compileall.py
@@ -248,7 +248,7 @@
         self.assertEqual(b'', quiet)
 
     def test_regexp(self):
-        self.assertRunOK('-q', '-x', 'ba[^\/]*$', self.pkgdir)
+        self.assertRunOK('-q', '-x', r'ba[^\/]*$', self.pkgdir)
         self.assertNotCompiled(self.barfn)
         self.assertCompiled(self.initfn)