diff --git a/mercator/__init__.py b/mercator/__init__.py
index 8827e86..79470f2 100644
--- a/mercator/__init__.py
+++ b/mercator/__init__.py
@@ -121,15 +121,16 @@ def cast(self, value):
         :param value: a python object that is compatible with the given ``target_type``
         :returns: list of items target type coerced into the ``target_type``. Supports ProtoMappings by automatically calling :py:meth:`~mercator.ProtoMapping.to_protobuf`.
         """
-        result = super().cast(value)
-
-        if result is None:
+        if value is None:
             return
 
         if not isinstance(value, (list, tuple)):
             raise TypeCastError(f'ProtoList.cast() received a non-list value '
                                 f'(type {type(value).__name__}): {value}')
 
+        if self.target_type is None:
+            return value
+
         if issubclass(self.target_type, ProtoMapping):
             return [self.target_type(item).to_protobuf() for item in value]
 
diff --git a/tests/unit/test_proto_list.py b/tests/unit/test_proto_list.py
index 3f8dec2..8984cd7 100644
--- a/tests/unit/test_proto_list.py
+++ b/tests/unit/test_proto_list.py
@@ -66,3 +66,37 @@ def test_proto_list_native_type():
     t1, t2 = result
     t1.should.be.a(str)
     t2.should.be.a(str)
+
+
+def test_proto_list_int_type():
+    "ProtoList() should return a list of integers if target_type is int"
+
+    field = ProtoList('user_ids', int)
+    result = field.cast(['1', 2])
+
+    result.should.be.a(list)
+    result.should.have.length_of(2)
+    result.should.equal([1, 2])
+
+    t1, t2 = result
+    t1.should.be.a(int)
+    t2.should.be.a(int)
+
+
+def test_proto_list_with_target_type_none():
+    "ProtoList() cast should return an origin value if target_type is None"
+    field = ProtoList('user_ids')
+    result = field.cast(['1', 2])
+
+    result.should.be.a(list)
+    result.should.have.length_of(2)
+    result.should.equal(['1', 2])
+
+
+def test_proto_list_with_target_type_none_and_non_list_tuple():
+    "ProtoList() should raise an error if target_type is None and not fed with a list or tuple"
+
+    field = ProtoList('tokens')
+    when_called = field.cast.when.called_with('some tokens as string')
+
+    when_called.should.have.raised(TypeCastError)