diff --git a/pywr_utils/model_runner.py b/pywr_utils/model_runner.py
index cc12f0f..eb46c8e 100644
--- a/pywr_utils/model_runner.py
+++ b/pywr_utils/model_runner.py
@@ -219,7 +219,7 @@ def run_incremental_sizes(max_zones=100, zone_increment=10, max_transfers=None,
     # Save results to CSV
     if results:
         df = pd.DataFrame(results)
-        output_path = os.path.join(output_dir, output_csv)
+        output_path = output_csv
         try:
             df.to_csv(output_path, index=False)
             print(f"\nResults saved to {os.path.abspath(output_path)}")
diff --git a/tests/integration/test_incremental_sweep_failures.py b/tests/integration/test_incremental_sweep_failures.py
index 9cf9dc0..f4f003b 100644
--- a/tests/integration/test_incremental_sweep_failures.py
+++ b/tests/integration/test_incremental_sweep_failures.py
@@ -117,10 +117,6 @@ def test_the_confirmed_summary_reports_its_size_on_disk(workdir, capsys):
     assert f"File size: {(workdir / 'timings.csv').stat().st_size} bytes" in output
 
 
-@pytest.mark.xfail(
-    strict=True,
-    reason="run_incremental_sizes joins the output directory onto a path that already contains it, so an output_csv with any directory component is written to <dir>/<dir>/<name> and the whole sweep's results are lost to an OSError after every model has already been run.",
-)
 def test_an_output_path_with_a_directory_component_is_written_where_it_was_asked_for(workdir):
     run_incremental_sizes(max_zones=2, zone_increment=2, transfer_increment=2, output_csv="results/timings.csv")