diff --git a/smartsim/_core/schemas/utils.py b/smartsim/_core/schemas/utils.py
index 3071df80a..3bf42f601 100644
--- a/smartsim/_core/schemas/utils.py
+++ b/smartsim/_core/schemas/utils.py
@@ -63,14 +63,14 @@ def _to_message(self, schema: _SchemaT) -> _Message[_SchemaT]:
 
     def from_string(self, str_: str) -> _SchemaT:
         try:
-            header, _ = str_.split(self._msg_delim, 1)
+            type_, _ = str_.split(self._msg_delim, 1)
         except ValueError:
-            _msg = f"Failed to find message header in string {repr(str_)}"
+            _msg = f"Failed determine schema type of string {repr(str_)}"
             raise ValueError(_msg) from None
         try:
-            cls = self._map[header]
+            cls = self._map[type_]
         except KeyError:
-            raise ValueError(f"No type of value `{header}` is registered") from None
+            raise ValueError(f"No type of value `{type_}` is registered") from None
         msg = _Message.from_str(str_, self._msg_delim, cls)
         return self._from_message(msg)
 
diff --git a/tests/utils/test_schema_utils.py b/tests/utils/test_schema_utils.py
index c63751e65..d17956f97 100644
--- a/tests/utils/test_schema_utils.py
+++ b/tests/utils/test_schema_utils.py
@@ -73,8 +73,15 @@ def test_registry_errors_on_unknown_schema():
         registry.to_string(Book(title="The Shortest Story of All Time", num_pages=1))
 
 
-def test_registry_correctly_maps_to_expected_type():
-    registry = SchemaRegistry()
+@pytest.mark.parametrize(
+    "delim",
+    (
+        pytest.param(SchemaRegistry._DEFAULT_DELIMITER, id="default delimiter"),
+        pytest.param("::", id="custom delimiter"),
+    ),
+)
+def test_registry_correctly_maps_to_expected_type(delim):
+    registry = SchemaRegistry(delim)
     registry.register("person")(Person)
     registry.register("book")(Book)
     person = Person(name="Bob", age=36)