diff --git a/src/caosdb/configuration.py b/src/caosdb/configuration.py
index 51e3749aaca3045afec9334ef987a174d5d19f26..314a1a1d0eb25091333c7b5528e32512a3679d96 100644
--- a/src/caosdb/configuration.py
+++ b/src/caosdb/configuration.py
@@ -84,16 +84,14 @@ def config_to_yaml(config):
 
 
 def validate_yaml_schema(valobj):
-    # TODO: Re-enable warning once the schema has been extended to also cover
-    # SSS pycaosdb.inis and integration tests.
     if optional_jsonschema_validate:
         with open(os.path.join(os.path.dirname(__file__), "schema-pycaosdb-ini.yml")) as f:
             schema = yaml.load(f, Loader=yaml.SafeLoader)
         optional_jsonschema_validate(instance=valobj, schema=schema["schema-pycaosdb-ini"])
-    # else:
-    #     warnings.warn("""
-    #                     Warning: The validation could not be performed because `jsonschema` is not installed.
-    #                 """)
+    else:
+        warnings.warn("""
+                        Warning: The validation could not be performed because `jsonschema` is not installed.
+                    """)
 
 
 def _read_config_files():