diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index ac8d67d..f21c82c 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -1397,7 +1397,7 @@ class _SubTest(TestCase):
 
     def _subDescription(self):
         parts = []
-        if self._message:
+        if self._message is not None:
             parts.append("[{}]".format(self._message))
         if self.params:
             params_desc = ', '.join(