diff --git a/apitools/base/protorpclite/protojson_test.py b/apitools/base/protorpclite/protojson_test.py
index 2eb46fa8..7a8f8750 100644
--- a/apitools/base/protorpclite/protojson_test.py
+++ b/apitools/base/protorpclite/protojson_test.py
@@ -51,6 +51,10 @@ class Nested(messages.Message):
 
         nested_value = messages.StringField(1)
 
+    class NestedDatetime(messages.Message):
+
+        nested_dt_value = message_types.DateTimeField(1)
+
     a_string = messages.StringField(2)
     an_integer = messages.IntegerField(3)
     a_float = messages.FloatField(4)
@@ -63,6 +67,7 @@ class Nested(messages.Message):
     a_repeated_datetime = message_types.DateTimeField(11, repeated=True)
     a_custom = CustomField(12)
     a_repeated_custom = CustomField(13, repeated=True)
+    a_nested_datetime = messages.MessageField(NestedDatetime, 14)
 
 
 class ModuleInterfaceTest(test_util.ModuleInterfaceTest,
@@ -368,6 +373,16 @@ def testDecodeInvalidDateTime(self):
         self.assertRaises(messages.DecodeError, protojson.decode_message,
                           MyMessage, '{"a_datetime": "invalid"}')
 
+    def testDecodeInvalidMessage(self):
+        encoded = """{
+        "a_nested_datetime": {
+          "nested_dt_value": "invalid"
+          }
+        }
+        """
+        self.assertRaises(messages.DecodeError, protojson.decode_message,
+                          MyMessage, encoded)
+
     def testEncodeDateTime(self):
         for datetime_string, datetime_vals in (
                 ('2012-09-30T15:31:50.262000',