diff --git a/test/test_train_allele_specific_models_command.py b/test/test_train_allele_specific_models_command.py
index 41fa9e3f88d3acdb365fbb2eb957c87573ddead8..5c3fbcfc961d1e2690c6dc46ca79262b11fe3451 100644
--- a/test/test_train_allele_specific_models_command.py
+++ b/test/test_train_allele_specific_models_command.py
@@ -53,7 +53,7 @@ def test_run():
     try:
         models_dir = tempfile.mkdtemp(prefix="mhcflurry-test-models")
         hyperparameters_filename = os.path.join(
-            models_dir, "hyperparameters.json")
+            models_dir, "hyperparameters.yaml")
         with open(hyperparameters_filename, "w") as fd:
             json.dump(HYPERPARAMETERS, fd)