diff --git a/betterproto/plugin.py b/betterproto/plugin.py
index 7476b38..2184a9c 100755
--- a/betterproto/plugin.py
+++ b/betterproto/plugin.py
@@ -1,12 +1,11 @@
 #!/usr/bin/env python
 
 import itertools
-import json
 import os.path
-import re
 import sys
 import textwrap
-from typing import Any, List, Tuple
+from collections import defaultdict
+from typing import Dict, List, Optional, Type
 
 try:
     import black
@@ -24,33 +23,23 @@ from google.protobuf.descriptor_pb2 import (
     DescriptorProto,
     EnumDescriptorProto,
     FieldDescriptorProto,
-    FileDescriptorProto,
-    ServiceDescriptorProto,
 )
 
 from betterproto.casing import safe_snake_case
 
-import google.protobuf.wrappers_pb2
+import google.protobuf.wrappers_pb2 as google_wrappers
 
-
-WRAPPER_TYPES = {
-    google.protobuf.wrappers_pb2.DoubleValue: "float",
-    google.protobuf.wrappers_pb2.FloatValue: "float",
-    google.protobuf.wrappers_pb2.Int64Value: "int",
-    google.protobuf.wrappers_pb2.UInt64Value: "int",
-    google.protobuf.wrappers_pb2.Int32Value: "int",
-    google.protobuf.wrappers_pb2.UInt32Value: "int",
-    google.protobuf.wrappers_pb2.BoolValue: "bool",
-    google.protobuf.wrappers_pb2.StringValue: "str",
-    google.protobuf.wrappers_pb2.BytesValue: "bytes",
-}
-
-
-def get_wrapper_type(type_name: str) -> (Any, str):
-    for wrapper, wrapped_type in WRAPPER_TYPES.items():
-        if wrapper.DESCRIPTOR.full_name == type_name:
-            return wrapper, wrapped_type
-    return None, None
+WRAPPER_TYPES: Dict[str, Optional[Type]] = defaultdict(lambda: None, {
+    'google.protobuf.DoubleValue': google_wrappers.DoubleValue,
+    'google.protobuf.FloatValue': google_wrappers.FloatValue,
+    'google.protobuf.Int64Value': google_wrappers.Int64Value,
+    'google.protobuf.UInt64Value': google_wrappers.UInt64Value,
+    'google.protobuf.Int32Value': google_wrappers.Int32Value,
+    'google.protobuf.UInt32Value': google_wrappers.UInt32Value,
+    'google.protobuf.BoolValue': google_wrappers.BoolValue,
+    'google.protobuf.StringValue': google_wrappers.StringValue,
+    'google.protobuf.BytesValue': google_wrappers.BytesValue,
+})
 
 
 def get_ref_type(package: str, imports: set, type_name: str, unwrap: bool = True) -> str:
@@ -64,20 +53,21 @@ def get_ref_type(package: str, imports: set, type_name: str, unwrap: bool = True
     type_name = type_name.lstrip(".")
 
     # Check if type is wrapper.
-    wrapper, wrapped_type = get_wrapper_type(type_name)
+    wrapper_class = WRAPPER_TYPES[type_name]
 
     if unwrap:
-        if wrapper:
-            return f"Optional[{wrapped_type}]"
+        if wrapper_class:
+            wrapped_type = type(wrapper_class().value)
+            return f"Optional[{wrapped_type.__name__}]"
 
         if type_name == "google.protobuf.Duration":
             return "timedelta"
 
         if type_name == "google.protobuf.Timestamp":
             return "datetime"
-    elif wrapper:
-        imports.add(f"from {wrapper.__module__} import {wrapper.__name__}")
-        return f"{wrapper.__name__}"
+    elif wrapper_class:
+        imports.add(f"from {wrapper_class.__module__} import {wrapper_class.__name__}")
+        return f"{wrapper_class.__name__}"
 
     if type_name.startswith(package):
         parts = type_name.lstrip(package).lstrip(".").split(".")