diff --git a/snapcraft/parts/lifecycle.py b/snapcraft/parts/lifecycle.py
index bb104b6637..2eff42764e 100644
--- a/snapcraft/parts/lifecycle.py
+++ b/snapcraft/parts/lifecycle.py
@@ -565,7 +565,6 @@ def _run_in_provider(
         project_name=project.name,
         project_path=project_path,
         base_configuration=base_configuration,
-        build_base=build_base.value,
         instance_name=instance_name,
         allow_unstable=allow_unstable,
     ) as instance:
diff --git a/tests/unit/conftest.py b/tests/unit/conftest.py
index 880a7aec41..dad56c2d7c 100644
--- a/tests/unit/conftest.py
+++ b/tests/unit/conftest.py
@@ -354,7 +354,7 @@ def launched_environment(
             project_name: str,
             project_path: Path,
             base_configuration: Base,
-            build_base: str,
+            build_base: Optional[str] = None,
             instance_name: str,
             allow_unstable: bool = False,
         ):
diff --git a/tests/unit/parts/test_lifecycle.py b/tests/unit/parts/test_lifecycle.py
index 3197bc6d2a..34c9ee7c09 100644
--- a/tests/unit/parts/test_lifecycle.py
+++ b/tests/unit/parts/test_lifecycle.py
@@ -1226,7 +1226,6 @@ def test_lifecycle_run_in_provider_default(
         project_name="mytest",
         project_path=ANY,
         base_configuration=mock_base_configuration,
-        build_base="22.04",
         instance_name="test-instance-name",
         allow_unstable=False,
     )
@@ -1350,7 +1349,6 @@ def test_lifecycle_run_in_provider_all_options(
         project_name="mytest",
         project_path=ANY,
         base_configuration=mock_base_configuration,
-        build_base="22.04",
         instance_name="test-instance-name",
         allow_unstable=False,
     )
@@ -1452,7 +1450,6 @@ def test_lifecycle_run_in_provider(
         project_name="mytest",
         project_path=ANY,
         base_configuration=mock_base_configuration,
-        build_base=BuilddBaseAlias.JAMMY.value,
         instance_name="test-instance-name",
         allow_unstable=False,
     )