diff --git a/src/pytest_split/plugin.py b/src/pytest_split/plugin.py
index fca0750..f65b9a6 100644
--- a/src/pytest_split/plugin.py
+++ b/src/pytest_split/plugin.py
@@ -214,7 +214,7 @@ def pytest_sessionfinish(self) -> None:
                 self.cached_durations[k] = v
 
         with open(self.config.option.durations_path, "w") as f:
-            json.dump(self.cached_durations, f)
+            json.dump(self.cached_durations, f, sort_keys=True, indent=4)
 
         message = self.writer.markup(
             "\n\n[pytest-split] Stored test durations in {}".format(self.config.option.durations_path)
diff --git a/tests/test_plugin.py b/tests/test_plugin.py
index 82807cd..de2a923 100644
--- a/tests/test_plugin.py
+++ b/tests/test_plugin.py
@@ -30,6 +30,7 @@ def test_it_stores(self, example_suite, durations_path):
 
         assert list(durations.keys()) == [
             "test_it_stores.py::test_1",
+            "test_it_stores.py::test_10",
             "test_it_stores.py::test_2",
             "test_it_stores.py::test_3",
             "test_it_stores.py::test_4",
@@ -38,7 +39,6 @@ def test_it_stores(self, example_suite, durations_path):
             "test_it_stores.py::test_7",
             "test_it_stores.py::test_8",
             "test_it_stores.py::test_9",
-            "test_it_stores.py::test_10",
         ]
 
         for duration in durations.values():