diff --git a/CHANGES.md b/CHANGES.md
index 2a796d1..92be4f2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,7 +4,7 @@ Changes
 development (main)
 ------------------
 
--
+- Fix dump functions failing to write nested `Configuration` instances in TOML format.
 
 0.17.1 (2025-10-15)
 -------------------
diff --git a/confidence/formats.py b/confidence/formats.py
index 9e74266..7ecdda8 100644
--- a/confidence/formats.py
+++ b/confidence/formats.py
@@ -84,6 +84,7 @@ def loads(self, string: str) -> typing.Any:
             return tomlkit.value(string)
 
     def dumps(self, value: typing.Any) -> str:
+        value = unwrap(value)
         try:
             # attempt to dump the value as TOML document
             return tomlkit.dumps(value)
diff --git a/tests/test_formats.py b/tests/test_formats.py
index 8ce8586..cec608e 100644
--- a/tests/test_formats.py
+++ b/tests/test_formats.py
@@ -2,6 +2,7 @@
 
 import pytest
 
+from confidence import Configuration, unwrap
 from confidence.formats import JSON, TOML, YAML
 
 
@@ -16,12 +17,24 @@ def test_singular_value_roundtrip(format, value):
 
 
 @pytest.mark.parametrize('format', (JSON, TOML, YAML, YAML(suffix='.conf', encoding='utf-32')))
-@pytest.mark.parametrize('value', ([], {}, [1, 2, 'a'], {'a': 1, 'b': 42.0, 'c': {'d': 'str'}, 'e': [{'g': True}]}))
+@pytest.mark.parametrize(
+    'value',
+    (
+        [],
+        {},
+        [1, 2, 'a'],
+        {'a': 1, 'b': 42.0, 'c': {'d': 'str'}, 'e': [{'g': True}]},
+        # nested configuration object should get unwrapped before serialization
+        Configuration({'a.b.c': 42}),
+        # serialization should not be trying to resolve references, this one would cause a recursion error if it does
+        Configuration({'a.b': [1, 2, '${a}']}),
+    ),
+)
 def test_multiple_values_roundtrip(format, value, tmp_path):
     fname = tmp_path / f'config{format.suffix}'
 
     format.dumpf(value, fname)
-    assert format.loadf(fname) == value
+    assert format.loadf(fname) == unwrap(value)
 
 
 def test_edit_format():