diff --git a/osh/word_eval_test.py b/osh/word_eval_test.py
index 6e26637888..05ebd91b45 100755
--- a/osh/word_eval_test.py
+++ b/osh/word_eval_test.py
@@ -34,7 +34,6 @@ class WordEvalTest(unittest.TestCase):
 
   def testEvalWordSequence_Errors(self):
     CASES = [
-        'readonly a+=1',
         'readonly a[x]=1',
         'readonly $binding a[x]=1',
         # There's no word elision!  This will be a parse error