diff --git a/third_party/2and3/yaml/__init__.pyi b/third_party/2and3/yaml/__init__.pyi
index ac8dd0274..50802e428 100644
--- a/third_party/2and3/yaml/__init__.pyi
+++ b/third_party/2and3/yaml/__init__.pyi
@@ -1,5 +1,5 @@
 import sys
-from typing import IO, Any, Iterator, Optional, Sequence, Text, Union, overload
+from typing import IO, Any, Callable, Iterator, Optional, Sequence, Text, Union, overload
 
 from yaml.dumper import *  # noqa: F403
 from yaml.error import *  # noqa: F403
@@ -256,7 +256,7 @@ def safe_dump(
 ) -> _Yaml: ...
 def add_implicit_resolver(tag, regexp, first=..., Loader=..., Dumper=...): ...
 def add_path_resolver(tag, path, kind=..., Loader=..., Dumper=...): ...
-def add_constructor(tag, constructor, Loader=...): ...
+def add_constructor(tag: _Str, constructor: Callable[[Loader, Node], Any], Loader: Loader = ...): ...
 def add_multi_constructor(tag_prefix, multi_constructor, Loader=...): ...
 def add_representer(data_type, representer, Dumper=...): ...
 def add_multi_representer(data_type, multi_representer, Dumper=...): ...
diff --git a/third_party/2and3/yaml/constructor.pyi b/third_party/2and3/yaml/constructor.pyi
index 8ea89c615..f1aeeee19 100644
--- a/third_party/2and3/yaml/constructor.pyi
+++ b/third_party/2and3/yaml/constructor.pyi
@@ -1,7 +1,10 @@
 import sys
-from typing import Any
+from typing import Any, Text, Union
 
 from yaml.error import MarkedYAMLError
+from yaml.nodes import ScalarNode
+
+_Scalar = Union[Text, int, float, bool, None]
 
 class ConstructorError(MarkedYAMLError): ...
 
@@ -15,10 +18,10 @@ class BaseConstructor:
     def __init__(self) -> None: ...
     def check_data(self): ...
     def get_data(self): ...
-    def get_single_data(self): ...
+    def get_single_data(self) -> Any: ...
     def construct_document(self, node): ...
     def construct_object(self, node, deep=...): ...
-    def construct_scalar(self, node): ...
+    def construct_scalar(self, node: ScalarNode) -> _Scalar: ...
     def construct_sequence(self, node, deep=...): ...
     def construct_mapping(self, node, deep=...): ...
     def construct_pairs(self, node, deep=...): ...
@@ -28,7 +31,7 @@ class BaseConstructor:
     def add_multi_constructor(cls, tag_prefix, multi_constructor): ...
 
 class SafeConstructor(BaseConstructor):
-    def construct_scalar(self, node): ...
+    def construct_scalar(self, node: ScalarNode) -> _Scalar: ...
     def flatten_mapping(self, node): ...
     def construct_mapping(self, node, deep=...): ...
     def construct_yaml_null(self, node): ...