diff --git a/declearn/utils/_toml_config.py b/declearn/utils/_toml_config.py
index bbbbb550e7f6609510b9938a337345f8e7bd2303..1156dc32c7f144c37caaecf92edae454bb1782e6 100644
--- a/declearn/utils/_toml_config.py
+++ b/declearn/utils/_toml_config.py
@@ -285,7 +285,7 @@ class TomlConfig:
         """
         # Case of valid inputs: return them as-is (including valid None).
         if _isinstance_generic(
-            inputs, field.type    # type: ignore  # update when py >=3.9
+            inputs, field.type  # type: ignore  # update when py >=3.9
         ):  # see function's notes
             return inputs
         # Case of None inputs: return default value if any, else raise.