diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 3d15571688..46fad4ce81 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -712,7 +712,7 @@ def notrun(reason):
     # Each test in qemu-iotests has a number ("seq")
     seq = os.path.basename(sys.argv[0])
 
-    open('%s/%s.notrun' % (output_dir, seq), 'wb').write(reason + '\n')
+    open('%s/%s.notrun' % (output_dir, seq), 'w').write(reason + '\n')
     print('%s not run: %s' % (seq, reason))
     sys.exit(0)