diff --git a/temporalio/converter.py b/temporalio/converter.py
index 45b2c8cc1..48502c8d4 100644
--- a/temporalio/converter.py
+++ b/temporalio/converter.py
@@ -1277,6 +1277,14 @@ def value_to_type(hint: Type, value: Any) -> Any:
                 )
             return hint(value)
 
+    # String Subtype
+    if inspect.isclass(hint) and issubclass(hint, str):
+        if not isinstance(value, str):
+            raise TypeError(
+                f"Cannot convert to {hint}, value not a string, value is {type(value)}"
+            )
+        return hint(value)
+
     # UUID
     if inspect.isclass(hint) and issubclass(hint, uuid.UUID):
         return hint(value)
diff --git a/tests/test_converter.py b/tests/test_converter.py
index 027ec5cbe..f106ed3e0 100644
--- a/tests/test_converter.py
+++ b/tests/test_converter.py
@@ -61,6 +61,13 @@ class SerializableStrEnum(StrEnum):
         FOO = "foo"
 
 
+class StringSubtype(str):
+  pass
+
+class StringEnumOldStyle(str, Enum):
+    FOO = "foo"
+
+
 @dataclass
 class MyDataClass:
     foo: str
@@ -363,6 +370,10 @@ def fail(hint: Type, value: Any) -> None:
             [SerializableStrEnum.FOO, SerializableStrEnum.FOO],
         )
 
+    # String Subtype
+    ok(StringSubtype, StringSubtype("abc"))
+    ok(StringEnumOldStyle, StringEnumOldStyle.FOO)
+
     # 3.10+ checks
     if sys.version_info >= (3, 10):
         ok(list[int], [1, 2])