diff --git a/src/graphql/execution/middleware.py b/src/graphql/execution/middleware.py
index 334a088a..d75243e6 100644
--- a/src/graphql/execution/middleware.py
+++ b/src/graphql/execution/middleware.py
@@ -20,7 +20,7 @@ class MiddlewareManager:
     must be aware of this and check whether values are awaitable before awaiting them.
     """
 
-    __slots__ = "middlewares", "_middleware_resolvers", "_cached_resolvers"
+    __slots__ = "__weakref__", "__dict__", "middlewares", "_middleware_resolvers", "_cached_resolvers"
 
     _cached_resolvers: Dict[GraphQLFieldResolver, GraphQLFieldResolver]
     _middleware_resolvers: Optional[List[Callable]]
diff --git a/src/graphql/language/ast.py b/src/graphql/language/ast.py
index a5da60c6..74e0c075 100644
--- a/src/graphql/language/ast.py
+++ b/src/graphql/language/ast.py
@@ -214,7 +214,7 @@ class OperationType(Enum):
 class Node:
     """AST nodes"""
 
-    __slots__ = ("loc",)
+    __slots__ = ("__dict__", "__weakref__", "loc",)
 
     loc: Optional[Location]
 
diff --git a/src/graphql/language/source.py b/src/graphql/language/source.py
index 9b0e0c42..7f942d93 100644
--- a/src/graphql/language/source.py
+++ b/src/graphql/language/source.py
@@ -6,7 +6,7 @@
 class Source:
     """A representation of source input to GraphQL."""
 
-    __slots__ = "body", "name", "location_offset"
+    __slots__ = "__weakref__", "__dict__", "body", "name", "location_offset"
 
     def __init__(
         self,
diff --git a/tests/language/test_ast.py b/tests/language/test_ast.py
index e9162e98..aa965d57 100644
--- a/tests/language/test_ast.py
+++ b/tests/language/test_ast.py
@@ -1,4 +1,5 @@
 from copy import copy, deepcopy
+import weakref
 
 from graphql.language import Location, Node, Source, Token, TokenKind
 from graphql.pyutils import inspect
@@ -224,3 +225,13 @@ class Foo(Node):
 
     def provides_keys_as_class_attribute():
         assert SampleTestNode.keys == ["loc", "alpha", "beta"]
+
+    def can_weakref():
+        node = SampleTestNode(alpha=1, beta=2)
+        wr = weakref.ref(node)  # That this works is 90% of the test
+        assert wr() is node
+
+    def can_make_attrs():
+        node = SampleTestNode(alpha=1, beta=2)
+        node.__new_random_attr = "Hello!"  # That this works is 90% of the test
+        assert node.__new_random_attr == "Hello!"