diff --git a/test/subset/run-tests.py b/test/subset/run-tests.py
index b0054802f..326951620 100755
--- a/test/subset/run-tests.py
+++ b/test/subset/run-tests.py
@@ -47,19 +47,26 @@ def run_test(test):
 	if return_code:
 		return fail_test(test, cli_args, "%s returned %d" % (' '.join(cli_args), return_code))
 
-	expected = read_binary(os.path.join(test_suite.get_output_directory(),
+        expected_ttx, return_code = run_ttx(os.path.join(test_suite.get_output_directory(),
 					    test.get_font_name()))
-	actual = read_binary(out_file)
+        if return_code:
+		return fail_test(test, cli_args, "ttx (expected) returned %d" % (return_code))
 
-	if len(actual) != len(expected):
-		return fail_test(test, cli_args, "expected %d bytes, actual %d: %s" % (
-				len(expected), len(actual), ' '.join(cli_args)))
+        actual_ttx, return_code = run_ttx(out_file)
+        if return_code:
+		return fail_test(test, cli_args, "ttx (actual) returned %d" % (return_code))
 
-	if not actual == expected:
-		return fail_test(test, cli_args, 'files are the same length but not the same bytes')
+	if not actual_ttx == expected_ttx:
+		return fail_test(test, cli_args, 'ttx for expected and actual does not match.')
 
 	return 0
 
+def run_ttx(file):
+        cli_args = ["ttx",
+                    "-o-",
+                    file]
+        return cmd(cli_args)
+
 
 args = sys.argv[1:]
 if not args or sys.argv[1].find('hb-subset') == -1 or not os.path.exists (sys.argv[1]):