diff --git a/ruyi/config/errors.py b/ruyi/config/errors.py
index 1e42109..dc8524c 100644
--- a/ruyi/config/errors.py
+++ b/ruyi/config/errors.py
@@ -48,7 +48,7 @@ def __repr__(self) -> str:
 class InvalidConfigValueError(ValueError):
     def __init__(
         self,
-        key: str | Sequence[str],
+        key: str | Sequence[str] | type,
         val: object | None,
     ) -> None:
         super().__init__()
@@ -56,7 +56,9 @@ def __init__(
         self._val = val
 
     def __str__(self) -> str:
-        return f"invalid value for config key {self._key}: {self._val}"
+        if isinstance(self._key, type):
+            return f"invalid config value for type {self._key}: {self._val}"
+        return f"invalid config value for key {self._key}: {self._val}"
 
     def __repr__(self) -> str:
         return f"InvalidConfigValueError({self._key:!r}, {self._val:!r})"
diff --git a/ruyi/config/schema.py b/ruyi/config/schema.py
index 7456c80..a034c3c 100644
--- a/ruyi/config/schema.py
+++ b/ruyi/config/schema.py
@@ -159,13 +159,17 @@ def encode_value(v: object) -> str:
 
 
 def decode_value(
-    key: str | Sequence[str],
+    key: str | Sequence[str] | type,
     val: str,
 ) -> object:
     """Decodes the given string representation of a config value into a Python
     value, directed by type information implied by the config key."""
 
-    expected_type = get_expected_type_for_config_key(key)
+    if isinstance(key, type):
+        expected_type = key
+    else:
+        expected_type = get_expected_type_for_config_key(key)
+
     if expected_type is bool:
         if val in ("true", "yes", "1"):
             return True
diff --git a/tests/config/test_schema.py b/tests/config/test_schema.py
index f40e358..35c2010 100644
--- a/tests/config/test_schema.py
+++ b/tests/config/test_schema.py
@@ -8,21 +8,24 @@
 
 def test_decode_value_bool() -> None:
     assert decode_value("installation.externally_managed", "true") is True
-    assert decode_value("installation.externally_managed", "false") is False
-    assert decode_value("installation.externally_managed", "yes") is True
-    assert decode_value("installation.externally_managed", "no") is False
-    assert decode_value("installation.externally_managed", "1") is True
-    assert decode_value("installation.externally_managed", "0") is False
+
+    assert decode_value(bool, "true") is True
+    assert decode_value(bool, "false") is False
+    assert decode_value(bool, "yes") is True
+    assert decode_value(bool, "no") is False
+    assert decode_value(bool, "1") is True
+    assert decode_value(bool, "0") is False
     with pytest.raises(InvalidConfigValueError):
-        decode_value("installation.externally_managed", "invalid")
+        decode_value(bool, "invalid")
     with pytest.raises(InvalidConfigValueError):
-        decode_value("installation.externally_managed", "x")
+        decode_value(bool, "x")
     with pytest.raises(InvalidConfigValueError):
-        decode_value("installation.externally_managed", "True")
+        decode_value(bool, "True")
 
 
 def test_decode_value_str() -> None:
     assert decode_value("repo.branch", "main") == "main"
+    assert decode_value(str, "main") == "main"
 
 
 def test_decode_value_datetime() -> None:
@@ -30,9 +33,10 @@ def test_decode_value_datetime() -> None:
     assert (
         decode_value("telemetry.upload_consent", "2024-12-01T12:00:00Z") == tz_aware_dt
     )
+    assert decode_value(datetime.datetime, "2024-12-01T12:00:00Z") == tz_aware_dt
 
     # naive datetimes are decoded using the implicit local timezone
-    decode_value("telemetry.upload_consent", "2024-12-01T12:00:00")
+    decode_value(datetime.datetime, "2024-12-01T12:00:00")
 
 
 def test_encode_value_bool() -> None: