diff --git a/test_runner/regress/test_compatibility.py b/test_runner/regress/test_compatibility.py
index 1f0940cab7..100027048f 100644
--- a/test_runner/regress/test_compatibility.py
+++ b/test_runner/regress/test_compatibility.py
@@ -177,7 +177,7 @@ def test_backward_compatibility(
         cli.raw_cli(["start"])
         request.addfinalizer(lambda: cli.raw_cli(["stop"]))
 
-        result = cli.pg_start("main")
+        result = cli.pg_start("main", port=port_distributor.get_port())
         request.addfinalizer(lambda: cli.pg_stop("main"))
     except Exception:
         breaking_changes_allowed = (