diff --git a/requirements/base.txt b/requirements/base.txt
index 614d435..135561f 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -1 +1 @@
-simplejson==3.17.2
+simplejson==3.18.4
diff --git a/tests/test_bootstrap.py b/tests/test_bootstrap.py
index 9077304..fd56d9f 100644
--- a/tests/test_bootstrap.py
+++ b/tests/test_bootstrap.py
@@ -1478,11 +1478,11 @@ def test_run(self, mock_runtime_client, mock_handle_event_request):
         "awslambdaric.bootstrap.LambdaLoggerHandler",
         Mock(side_effect=Exception("Boom!")),
     )
-    @patch("awslambdaric.bootstrap.build_fault_result", MagicMock())
+    @patch("awslambdaric.bootstrap.build_fault_result")
     @patch("awslambdaric.bootstrap.log_error", MagicMock())
     @patch("awslambdaric.bootstrap.LambdaRuntimeClient", MagicMock())
     @patch("awslambdaric.bootstrap.sys")
-    def test_run_exception(self, mock_sys):
+    def test_run_exception(self, mock_sys, mock_build_fault_result):
         class TestException(Exception):
             pass
 
@@ -1490,6 +1490,7 @@ class TestException(Exception):
         expected_handler = "app.my_test_handler"
         expected_lambda_runtime_api_addr = "test_addr"
 
+        mock_build_fault_result.return_value = {}
         mock_sys.exit.side_effect = TestException("Boom!")
 
         with self.assertRaises(TestException):