diff --git a/src/openjd/cli/_common/_validation_utils.py b/src/openjd/cli/_common/_validation_utils.py
index 9b051ff..19a0f62 100644
--- a/src/openjd/cli/_common/_validation_utils.py
+++ b/src/openjd/cli/_common/_validation_utils.py
@@ -15,11 +15,12 @@
 
 
 def get_doc_type(filepath: Path) -> DocumentType:
+    # If the file has a .json extension, treat it strictly
+    # as JSON, otherwise treat it as YAML.
     if filepath.suffix.lower() == ".json":
         return DocumentType.JSON
-    elif filepath.suffix.lower() in (".yaml", ".yml"):
+    else:
         return DocumentType.YAML
-    raise RuntimeError(f"'{str(filepath)}' is not JSON or YAML.")
 
 
 def read_template(template_file: Path) -> dict[str, Any]:
diff --git a/test/openjd/cli/test_common.py b/test/openjd/cli/test_common.py
index ad21193..dad8dab 100644
--- a/test/openjd/cli/test_common.py
+++ b/test/openjd/cli/test_common.py
@@ -50,6 +50,7 @@ def template_dir_and_cwd():
     [
         pytest.param(".template.json", json.dump, id="Successful JSON"),
         pytest.param(".template.yaml", yaml.dump, id="Successful YAML"),
+        pytest.param(".ojdt", yaml.dump, id="Successful YAML with alternate extension"),
     ],
 )
 def test_read_template_success(tempfile_extension: str, doc_serializer: Callable):
@@ -119,6 +120,12 @@ def test_read_template_fileerror(
             'specificationVersion: "jobtemplate-2023-09"\n',
             id="YAML missing field",
         ),
+        pytest.param(
+            # Extensions other than .json are treated as YAML
+            ".template.ojdt",
+            'specificationVersion: "jobtemplate-2023-09"\n',
+            id="YAML missing field",
+        ),
     ],
 )
 def test_read_job_template_parsingerror(tempfile_extension: str, file_contents: str):
@@ -152,6 +159,12 @@ def test_read_job_template_parsingerror(tempfile_extension: str, file_contents:
             'specificationVersion: "environment-2023-09"\n',
             id="YAML missing field",
         ),
+        pytest.param(
+            # Extensions other than .json are treated as YAML
+            ".template.ojde",
+            'specificationVersion: "environment-2023-09"\n',
+            id="YAML missing field",
+        ),
     ],
 )
 def test_read_environment_template_parsingerror(tempfile_extension: str, file_contents: str):
@@ -243,15 +256,6 @@ def test_get_job_params_success(mock_param_args: list[str], expected_param_value
             "is not a file",
             id="Parameter filepath is not a file",
         ),
-        pytest.param(
-            ["file://some-image.png"],
-            True,
-            True,
-            "some-image.png",
-            None,
-            "is not JSON or YAML",
-            id="Parameter filepath is not JSON/YAML",
-        ),
         pytest.param(
             ["file://forbidden-file.json"],
             True,