diff --git a/src/griffe/loader.py b/src/griffe/loader.py
index 10fc3793..7842473f 100644
--- a/src/griffe/loader.py
+++ b/src/griffe/loader.py
@@ -211,7 +211,10 @@ def expand_exports(self, module: Module, seen: set | None = None) -> None:
                 next_module = self.modules_collection[module_path]
                 if next_module.path not in seen:
                     self.expand_exports(next_module, seen)
-                    expanded |= next_module.exports
+                    try:
+                        expanded |= next_module.exports
+                    except TypeError:
+                        logger.warning(f"Unsupported item in {module.path}.__all__: {export} (use strings only)")
             else:
                 expanded.add(export)
         module.exports = expanded
diff --git a/tests/test_loader.py b/tests/test_loader.py
index 2740ea66..565a43a3 100644
--- a/tests/test_loader.py
+++ b/tests/test_loader.py
@@ -235,3 +235,18 @@ def test_load_single_module_from_both_py_and_pyi_files():
         loader = GriffeLoader(search_paths=[tmp_folder.path])
         package = loader.load_module("mod")
         assert "f" in package.members
+
+
+def test_unsupported_item_in_all(caplog):
+    """Check that unsupported items in `__all__` log a warning.
+
+    Parameters:
+        caplog: Pytest fixture to capture logs.
+    """
+    item_name = "XXX"
+    with temporary_pypackage("package", ["mod.py"]) as tmp_folder:
+        tmp_folder.path.joinpath("__init__.py").write_text(f"from .mod import {item_name}\n__all__ = [{item_name}]")
+        tmp_folder.path.joinpath("mod.py").write_text(f"class {item_name}: ...")
+        loader = GriffeLoader(search_paths=[tmp_folder.tmpdir])
+        loader.expand_exports(loader.load_module("package"))
+    assert any(item_name in record.message and record.levelname == "WARNING" for record in caplog.records)