diff --git a/CHANGES.rst b/CHANGES.rst
index 677542e..b423276 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,12 @@
 Version history
 ===============
 
+**UNRELEASED**
+
+- Fix SQL Server schema reflection failing when encountering the ``sysname`` type
+  by registering it as ``NVARCHAR`` in the MSSQL dialect before reflection
+  (PR by @NotCarlosSerrano)
+
 **4.0.2**
 
 - Fixed rendering of inherited keyword arguments for dialect-specific types that use
diff --git a/src/sqlacodegen/cli.py b/src/sqlacodegen/cli.py
index 8f37373..8d74616 100644
--- a/src/sqlacodegen/cli.py
+++ b/src/sqlacodegen/cli.py
@@ -112,6 +112,17 @@ def main() -> None:
     # Use reflection to fill in the metadata
     engine_args = _parse_engine_args(args.engine_arg)
     engine = create_engine(args.url, **engine_args)
+
+    # Register missing SQL Server types
+    if engine.dialect.name == "mssql":
+        from sqlalchemy.sql.sqltypes import NVARCHAR
+
+        ischema_names: dict[str, type] | None = getattr(
+            engine.dialect, "ischema_names", None
+        )
+        if ischema_names is not None:
+            ischema_names.setdefault("sysname", NVARCHAR)
+
     metadata = MetaData()
     tables = args.tables.split(",") if args.tables else None
     schemas = args.schemas.split(",") if args.schemas else [None]