diff --git a/singer/utils.py b/singer/utils.py
index 4cd179d..3efdccf 100644
--- a/singer/utils.py
+++ b/singer/utils.py
@@ -185,6 +185,9 @@ def check_config(config, required_keys):
     if missing_keys:
         raise Exception("Config is missing required keys: {}".format(missing_keys))
 
+def update_config_file(config_path, new_config):
+    with open(config_path, 'w') as output:
+        output.write(json.dumps(new_config, indent=2))
 
 def backoff(exceptions, giveup):
     """Decorates a function to retry up to 5 times using an exponential backoff
diff --git a/tests/test_utils.py b/tests/test_utils.py
index bb26da6..0783510 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -3,7 +3,7 @@
 import pytz
 import logging
 import singer.utils as u
-
+import json
 
 class TestFormat(unittest.TestCase):
     def test_small_years(self):
@@ -33,3 +33,22 @@ def test_exception_fn(self):
         def foo():
             raise RuntimeError("foo")
         self.assertRaises(RuntimeError, foo)
+
+class TestUpdateConfig(unittest.TestCase):
+    def test_file_changed(self):
+        original_config = {'key_a': 'val_a'}
+
+        with open('config.json', 'w') as file:
+            file.write(json.dumps(original_config))
+
+        changed_config = {'key_b': 'val_b'}
+
+        u.update_config_file('config.json', changed_config)
+
+        read_config = u.load_json('config.json')
+
+        self.assertEqual(changed_config.get('key_b'), read_config.get('key_b'))
+
+    def tearDown(self):
+        import os
+        os.remove('config.json')