diff --git a/pynamodb_attributes/__init__.py b/pynamodb_attributes/__init__.py
index 765f8c7..fc6d21e 100644
--- a/pynamodb_attributes/__init__.py
+++ b/pynamodb_attributes/__init__.py
@@ -12,6 +12,7 @@
 from .unicode_datetime import UnicodeDatetimeAttribute
 from .unicode_delimited_tuple import UnicodeDelimitedTupleAttribute
 from .unicode_enum import UnicodeEnumAttribute
+from .unicode_protobuf_enum import UnicodeProtobufEnumAttribute
 from .uuid import UUIDAttribute
 
 __all__ = [
@@ -22,6 +23,7 @@
     "IntegerEnumAttribute",
     "UnicodeDelimitedTupleAttribute",
     "UnicodeEnumAttribute",
+    "UnicodeProtobufEnumAttribute",
     "TimedeltaAttribute",
     "TimedeltaMsAttribute",
     "TimedeltaUsAttribute",
diff --git a/pynamodb_attributes/unicode_protobuf_enum.py b/pynamodb_attributes/unicode_protobuf_enum.py
index 66ee104..7d8517a 100644
--- a/pynamodb_attributes/unicode_protobuf_enum.py
+++ b/pynamodb_attributes/unicode_protobuf_enum.py
@@ -50,7 +50,7 @@ def __init__(
         enum_type: Type[_TProtobufEnum],
         *,
         unknown_value: Optional[_TProtobufEnum] = _fail,
-        prefix: str,
+        prefix: str = "",
         lower: bool = True,
         **kwargs: Any,
     ) -> None:
diff --git a/setup.cfg b/setup.cfg
index 5585f89..a8c5b1a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -4,7 +4,7 @@ universal = 1
 [metadata]
 license_file = LICENSE
 name = pynamodb-attributes
-version = 0.5.0
+version = 0.5.1
 description = Common attributes for PynamoDB
 long_description = file:README.md
 long_description_content_type = text/markdown
diff --git a/tests/unicode_protobuf_enum_attribute_test.py b/tests/unicode_protobuf_enum_attribute_test.py
index 7c2882f..071ad5d 100644
--- a/tests/unicode_protobuf_enum_attribute_test.py
+++ b/tests/unicode_protobuf_enum_attribute_test.py
@@ -10,7 +10,7 @@
 from pynamodb.models import Model
 from typing_extensions import assert_type
 
-from pynamodb_attributes.unicode_protobuf_enum import UnicodeProtobufEnumAttribute
+from pynamodb_attributes import UnicodeProtobufEnumAttribute
 from tests.connection import _connection
 from tests.meta import dynamodb_table_meta
 
@@ -85,6 +85,12 @@ class MyModel(Model):
         prefix="SHAKE_FLAVOR_",
         null=True,
     )
+    value_with_prefix = UnicodeProtobufEnumAttribute(
+        diner_pb2.ShakeFlavor,
+        unknown_value=diner_pb2.SHAKE_FLAVOR_UNKNOWN,
+        null=True,
+        lower=False,
+    )
     map_attr = MyMapAttr(null=True)
 
 
@@ -140,6 +146,7 @@ def test_serialization_unknown_value_success(uuid_key):
                 "value": {"S": "vanilla"},
                 "value_upper": {"S": "VANILLA"},
                 "value_with_unknown": {"S": "vanilla"},
+                "value_with_prefix": {"S": "SHAKE_FLAVOR_VANILLA"},
             },
         ),
         (
@@ -148,6 +155,7 @@ def test_serialization_unknown_value_success(uuid_key):
                 "value": {"S": "chocolate"},
                 "value_upper": {"S": "CHOCOLATE"},
                 "value_with_unknown": {"S": "chocolate"},
+                "value_with_prefix": {"S": "SHAKE_FLAVOR_CHOCOLATE"},
             },
         ),
     ],
@@ -162,6 +170,7 @@ def test_serialization(
     model.value = value
     model.value_upper = value
     model.value_with_unknown = value
+    model.value_with_prefix = value
     model.save()
 
     # verify underlying storage
@@ -173,6 +182,7 @@ def test_serialization(
     assert model.value == value
     assert model.value_upper == value
     assert model.value_with_unknown == value
+    assert model.value_with_prefix == value
 
 
 def test_map_attribute(  # exercises the __deepcopy__ method