diff --git a/external/mypy b/external/mypy
index d9dea5f..69a055a 160000
--- a/external/mypy
+++ b/external/mypy
@@ -1 +1 @@
-Subproject commit d9dea5f3ad30bb449e4167b3e8476684ded0482e
+Subproject commit 69a055a7632e2444fcb2bfb022d04f4546358d50
diff --git a/sqlalchemy-stubs/dialects/postgresql/base.pyi b/sqlalchemy-stubs/dialects/postgresql/base.pyi
index d910e5c..7858208 100644
--- a/sqlalchemy-stubs/dialects/postgresql/base.pyi
+++ b/sqlalchemy-stubs/dialects/postgresql/base.pyi
@@ -1,13 +1,20 @@
 from ... import schema
 from ...engine import default, reflection
 from ...sql import compiler, expression, sqltypes, type_api
-from typing import Any, Optional, Set, Type, Text, Pattern, Dict
+from typing import Any, Optional, Set, Type, Text, Pattern, Dict, TypeVar, overload
 from datetime import timedelta
+import uuid
+import sys
 
 from sqlalchemy.types import INTEGER as INTEGER, BIGINT as BIGINT, SMALLINT as SMALLINT, VARCHAR as VARCHAR, \
     CHAR as CHAR, TEXT as TEXT, FLOAT as FLOAT, NUMERIC as NUMERIC, \
     DATE as DATE, BOOLEAN as BOOLEAN, REAL as REAL
 
+if sys.version_info >= (3, 8):
+    from typing import Literal
+else:
+    from typing_extensions import Literal
+
 AUTOCOMMIT_REGEXP: Pattern[Text]
 RESERVED_WORDS: Set[str]
 
@@ -66,10 +73,17 @@ class BIT(sqltypes.TypeEngine[str]):
     def __init__(self, length: Optional[int] = ..., varying: bool = ...) -> None: ...
 PGBit = BIT
 
-class UUID(sqltypes.TypeEngine[str]):
+_T = TypeVar("_T")
+
+class UUID(sqltypes.TypeEngine[_T]):
     __visit_name__: str = ...
     as_uuid: bool = ...
-    def __init__(self, as_uuid: bool = ...) -> None: ...
+    @overload
+    def __new__(self, as_uuid: Literal[True]) -> UUID[sqltypes.TypeEngine[uuid.UUID]]: ...
+    @overload
+    def __new__(self, as_uuid: Literal[False, None]) -> UUID[sqltypes.TypeEngine[str]]: ...
+    @overload
+    def __new__(self) -> UUID[sqltypes.TypeEngine[str]]: ...
     def bind_processor(self, dialect: Any): ...
     def result_processor(self, dialect: Any, coltype: Any): ...
 PGUuid = UUID