diff --git a/src/openjd/model/v2023_09/_model.py b/src/openjd/model/v2023_09/_model.py
index ad099d6..9189bbb 100644
--- a/src/openjd/model/v2023_09/_model.py
+++ b/src/openjd/model/v2023_09/_model.py
@@ -351,6 +351,9 @@ class EnvironmentActions(OpenJDModel_v2023_09):
     @classmethod
     def _requires_oneof(cls, values: dict[str, Any]) -> dict[str, Any]:
         """A validator that runs on the model data before parsing."""
+        if not isinstance(values, dict):
+            raise ValueError("Expected a dictionary of values")
+
         on_enter = values.get("onEnter")
         on_exit = values.get("onExit")
         if on_enter is None and on_exit is None:
diff --git a/test/openjd/model/v2023_09/test_template_variables.py b/test/openjd/model/v2023_09/test_template_variables.py
index d01133f..2e6f43a 100644
--- a/test/openjd/model/v2023_09/test_template_variables.py
+++ b/test/openjd/model/v2023_09/test_template_variables.py
@@ -1128,6 +1128,17 @@ def test_job_template_variables_parse_success(data: dict[str, Any]) -> None:
         2,  # Validation of Job Foo & Task Foo
         id="all parameter symbols are defined when validation errors",
     ),
+    pytest.param(
+        {
+            "specificationVersion": "jobtemplate-2023-09",
+            "name": "Foo",
+            "parameterDefinitions": [FOO_PARAMETER_STRING],
+            "steps": [STEP_TEMPLATE_FOO],
+            "jobEnvironments": [{"name": "VariableEnv", "script": {"actions": []}}],
+        },
+        1,
+        id="jobEnvironments.script.actions needs to be a dict",
+    ),
 )