diff --git a/test/cryptsuite.py b/test/cryptsuite.py
index 773526fd..b3dbee3d 100755
--- a/test/cryptsuite.py
+++ b/test/cryptsuite.py
@@ -1833,10 +1833,17 @@ class standard_test_vectors(MyTestBase):
             self.assertEqual(crc32_rfc1662(vec), 0x2144DF1C)
 
 if __name__ == "__main__":
-    try:
-        unittest.main()
-    finally:
-        # On exit, make sure we check the subprocess's return status,
-        # so that if Leak Sanitiser detected any memory leaks, the
-        # test will turn into a failure at the last minute.
-        childprocess.check_return_status()
+    # Run the tests, suppressing automatic sys.exit and collecting the
+    # unittest.TestProgram instance returned by unittest.main instead.
+    testprogram = unittest.main(exit=False)
+
+    # If any test failed, just exit with failure status.
+    if not testprogram.result.wasSuccessful():
+        childprocess.wait_for_exit()
+        sys.exit(1)
+
+    # But if no tests failed, we have one last check to do: look at
+    # the subprocess's return status, so that if Leak Sanitiser
+    # detected any memory leaks, the success return status will turn
+    # into a failure at the last minute.
+    childprocess.check_return_status()
diff --git a/test/testcrypt.py b/test/testcrypt.py
index 95d311d9..659ea4ca 100644
--- a/test/testcrypt.py
+++ b/test/testcrypt.py
@@ -26,6 +26,7 @@ class ChildProcess(object):
     def __init__(self):
         self.sp = None
         self.debug = None
+        self.exitstatus = None
 
         dbg = os.environ.get("PUTTY_TESTCRYPT_DEBUG")
         if dbg is not None:
@@ -62,12 +63,16 @@ class ChildProcess(object):
             unicode_to_bytes(arg) for arg in args))
         argcount = int(self.read_line())
         return [self.read_line() for arg in range(argcount)]
+    def wait_for_exit(self):
+        if self.sp is not None:
+            self.sp.stdin.close()
+            self.exitstatus = self.sp.wait()
+            self.sp = None
     def check_return_status(self):
-        assert self.sp is not None
-        self.sp.stdin.close()
-        status = self.sp.wait()
-        if status != 0:
-            raise Exception("testcrypt returned exit status {}".format(status))
+        self.wait_for_exit()
+        if self.exitstatus is not None and self.exitstatus != 0:
+            raise Exception("testcrypt returned exit status {}"
+                            .format(self.exitstatus))
 
 childprocess = ChildProcess()