diff --git a/logstash_async/constants.py b/logstash_async/constants.py
index f04167c..37d0b21 100644
--- a/logstash_async/constants.py
+++ b/logstash_async/constants.py
@@ -32,11 +32,11 @@ class Constants:
     # Usually this list does not need to be modified. Add/Remove elements to
     # exclude/include them in the Logstash event, for the full list see:
     # http://docs.python.org/library/logging.html#logrecord-attributes
-    FORMATTER_RECORD_FIELD_SKIP_LIST = [
+    FORMATTER_RECORD_FIELD_SKIP_LIST = {
         'args', 'asctime', 'created', 'exc_info', 'exc_text', 'filename',
         'funcName', 'id', 'levelname', 'levelno', 'lineno', 'module',
         'msecs', 'msg', 'name', 'pathname', 'process',
-        'processName', 'relativeCreated', 'stack_info', 'thread', 'threadName']
+        'processName', 'relativeCreated', 'stack_info', 'thread', 'threadName'}
     # fields to be set on the top-level of a Logstash event/message, do not modify this
     # unless you know what you are doing
     FORMATTER_LOGSTASH_MESSAGE_FIELD_LIST = [
diff --git a/logstash_async/formatter.py b/logstash_async/formatter.py
index 173f7b1..83d2bfa 100644
--- a/logstash_async/formatter.py
+++ b/logstash_async/formatter.py
@@ -133,7 +133,9 @@ def _format_timestamp(self, time_):
 
     # ----------------------------------------------------------------------
     def _get_record_fields(self, record):
-        return {k: self._value_repr(v) for k, v in record.__dict__.items()}
+        return {k: self._value_repr(v)
+                for k, v in record.__dict__.items()
+                if k not in constants.FORMATTER_RECORD_FIELD_SKIP_LIST}
 
     # ----------------------------------------------------------------------
     def _value_repr(self, value):
diff --git a/tests/formatter_test.py b/tests/formatter_test.py
index 92a6ae4..1a004c0 100644
--- a/tests/formatter_test.py
+++ b/tests/formatter_test.py
@@ -29,6 +29,15 @@ def test_format(self):
 
         self.assertIsNone(file_handler.exception)
 
+    def test_fields_are_excluded_in_get_record_fields(self):
+        formatter = LogstashFormatter()
+        log_record = makeLogRecord({
+            'filename': 'foo.py',
+            'dummy': 'foobar'
+        })
+        self.assertDictEqual(formatter._get_record_fields(log_record), {
+            'dummy': 'foobar'
+        })
 
 if __name__ == "__main__":
     unittest.main()