diff --git a/pyoracle_forms/__init__.py b/pyoracle_forms/__init__.py
index 4214520..e401836 100644
--- a/pyoracle_forms/__init__.py
+++ b/pyoracle_forms/__init__.py
@@ -44,7 +44,7 @@
 from .misc import registered_objects
 from .property_types import Properties
 
-__version__ = "0.3.3"
+__version__ = "0.3.4"
 
 
 def initialize_context(version: str = "12c", encoding: str = "utf-8") -> None:
diff --git a/pyoracle_forms/context.py b/pyoracle_forms/context.py
index 2acff14..df345da 100644
--- a/pyoracle_forms/context.py
+++ b/pyoracle_forms/context.py
@@ -124,15 +124,24 @@ def _handled_api_function(*args: Any) -> Any:  # type: ignore
     return _handled_api_function
 
 
-def has_property(generic_object: BaseObject, property_number: int) -> bool:
-    func = api_function("d2fobhp_HasProp", (c_void_p, c_int))
-    result = func(generic_object, property_number)
-
+def handle_return_value(result: int) -> bool:
     if result in (2, 3):  # YES, NO
         return bool(result == 2)
     raise_for_code(result)
 
 
+def is_subclassed(generic_object: BaseObject) -> bool:
+    func = api_function("d2fobis_IsSubclassed", (c_void_p,))
+    result = func(generic_object)
+    return handle_return_value(result)
+
+
+def has_property(generic_object: BaseObject, property_number: int) -> bool:
+    func = api_function("d2fobhp_HasProp", (c_void_p, c_int))
+    result = func(generic_object, property_number)
+    return handle_return_value(result)
+
+
 def setter(function_name: str, setter_type: CTypes) -> Setter[T]:
     return handled_api_function(function_name, (c_void_p, c_int, setter_type))
 
@@ -223,9 +232,9 @@ def property_type(property_number: int) -> int:
 
 
 def property_constant_number(property_const_name: str) -> int:
-    return handled_api_function("d2fprgcv_GetConstValue", (c_char_p, c_void_p), 1)(
-        property_const_name.encode("utf-8"), c_int()
-    ).value
+    return handled_api_function(
+        "d2fprgcv_GetConstValue", (c_char_p, c_void_p), return_value_index=1
+    )(property_const_name.encode("utf-8"), c_int()).value
 
 
 def object_number(obj_name: str) -> int:
diff --git a/pyoracle_forms/generic_object.py b/pyoracle_forms/generic_object.py
index f93ac75..76997f3 100644
--- a/pyoracle_forms/generic_object.py
+++ b/pyoracle_forms/generic_object.py
@@ -11,6 +11,7 @@
 from .context import set_subclass
 from .context import move
 from .context import query_type
+from .context import is_subclassed
 
 from .property_types import Properties
 
@@ -112,8 +113,8 @@ def is_property_inherited(self, property_type: Properties) -> NoReturn:
     def is_property_default(self, property_type: Properties) -> NoReturn:
         raise NotImplementedError()
 
-    def is_subclassed(self) -> NoReturn:
-        raise NotImplementedError()
+    def is_subclassed(self) -> bool:
+        return is_subclassed(self)
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({repr(self._as_parameter_)})"
diff --git a/tests/test_item.py b/tests/test_item.py
index 2e9c86b..938a300 100644
--- a/tests/test_item.py
+++ b/tests/test_item.py
@@ -93,8 +93,3 @@ def test_is_property_inherited(new_item):
 @pytest.mark.xfail
 def test_is_property_default(new_item):
     assert new_item.is_property_default(Properties.x_position)
-
-
-@pytest.mark.xfail
-def test_is_subclassed(new_item):
-    assert new_item.is_subclassed()
diff --git a/tests/test_subclass.py b/tests/test_subclass.py
index aeecfeb..fdd3a28 100644
--- a/tests/test_subclass.py
+++ b/tests/test_subclass.py
@@ -11,3 +11,11 @@ def test_un_subclass(subclassed_item):
 
     assert subclass.source_object != subclass
     assert not subclassed_item.source_object
+
+
+def test_is_not_subclassed(new_item):
+    assert not new_item.is_subclassed()
+
+
+def test_is_subclassed(subclassed_item):
+    assert subclassed_item.is_subclassed()