diff --git a/tests/forward_models/rft/test_gendata_rft.py b/tests/forward_models/rft/test_gendata_rft.py
index 260dffef2..6389e4ab2 100644
--- a/tests/forward_models/rft/test_gendata_rft.py
+++ b/tests/forward_models/rft/test_gendata_rft.py
@@ -522,7 +522,7 @@ def test_ert_setup_one_well_one_rft_point(tmpdir):
     # pylint: disable=subprocess-run-check
     # (assert on the return code further down)
     result = subprocess.run(
-        ["ert", "ensemble_smoother", "--target-case", "default_1", "config.ert"],
+        ["ert", "ensemble_smoother", "--target-case", "default_%d", "config.ert"],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         check=False,