diff --git a/tools/parallel-capacity-test/parallel_capacity_test.py b/tools/parallel-capacity-test/parallel_capacity_test.py
index edfd1b9..1d86a09 100755
--- a/tools/parallel-capacity-test/parallel_capacity_test.py
+++ b/tools/parallel-capacity-test/parallel_capacity_test.py
@@ -135,7 +135,7 @@ class ParallelCapacityTester:
 
         try:
             result = subprocess.run(
-                ['opencode', 'run', task, '--workdir', workdir],
+                ['opencode', 'run', task, '--dir', workdir],
                 capture_output=True,
                 text=True,
                 timeout=self.timeout