diff --git a/stdlib/3/json/decoder.pyi b/stdlib/3/json/decoder.pyi
index d57a6a9fc..3eb4cf5d9 100644
--- a/stdlib/3/json/decoder.pyi
+++ b/stdlib/3/json/decoder.pyi
@@ -1,3 +1,4 @@
+import sys
 from typing import Any, Callable, Dict, List, Optional, Tuple
 
 class JSONDecodeError(ValueError):
@@ -16,11 +17,26 @@ class JSONDecoder:
     strict: bool
     object_pairs_hook: Callable[[List[Tuple[str, Any]]], Any]
 
-    def __init__(self, object_hook: Optional[Callable[[Dict[str, Any]], Any]] = ...,
-                 parse_float: Optional[Callable[[str], Any]] = ...,
-                 parse_int: Optional[Callable[[str], Any]] = ...,
-                 parse_constant: Optional[Callable[[str], Any]] = ...,
-                 strict: bool = ...,
-                 object_pairs_hook: Optional[Callable[[List[Tuple[str, Any]]], Any]] = ...) -> None: ...
-    def decode(self, s: str) -> Any: ...
+    if sys.version_info >= (3, 6):
+        def __init__(
+            self,
+            *,
+            object_hook: Optional[Callable[[Dict[str, Any]], Any]] = ...,
+            parse_float: Optional[Callable[[str], Any]] = ...,
+            parse_int: Optional[Callable[[str], Any]] = ...,
+            parse_constant: Optional[Callable[[str], Any]] = ...,
+            strict: bool = ...,
+            object_pairs_hook: Optional[Callable[[List[Tuple[str, Any]]], Any]] = ...
+        ) -> None: ...
+    else:
+        def __init__(
+            self,
+            object_hook: Optional[Callable[[Dict[str, Any]], Any]] = ...,
+            parse_float: Optional[Callable[[str], Any]] = ...,
+            parse_int: Optional[Callable[[str], Any]] = ...,
+            parse_constant: Optional[Callable[[str], Any]] = ...,
+            strict: bool = ...,
+            object_pairs_hook: Optional[Callable[[List[Tuple[str, Any]]], Any]] = ...,
+        ) -> None: ...
+    def decode(self, s: str, _w: Callable[..., Any] = ...) -> Any: ...  # _w is undocumented
     def raw_decode(self, s: str, idx: int = ...) -> Tuple[Any, int]: ...
diff --git a/stdlib/3/json/encoder.pyi b/stdlib/3/json/encoder.pyi
index 63f5ffebe..69e11e102 100644
--- a/stdlib/3/json/encoder.pyi
+++ b/stdlib/3/json/encoder.pyi
@@ -1,3 +1,4 @@
+import sys
 from typing import Any, Callable, Iterator, Optional, Tuple
 
 class JSONEncoder:
@@ -11,11 +12,31 @@ class JSONEncoder:
     sort_keys: bool
     indent: int
 
-    def __init__(self, skipkeys: bool = ..., ensure_ascii: bool = ...,
-                 check_circular: bool = ..., allow_nan: bool = ..., sort_keys: bool = ...,
-                 indent: Optional[int] = ..., separators: Optional[Tuple[str, str]] = ...,
-                 default: Optional[Callable[..., Any]] = ...) -> None: ...
-
+    if sys.version_info >= (3, 6):
+        def __init__(
+            self,
+            *,
+            skipkeys: bool = ...,
+            ensure_ascii: bool = ...,
+            check_circular: bool = ...,
+            allow_nan: bool = ...,
+            sort_keys: bool = ...,
+            indent: Optional[int] = ...,
+            separators: Optional[Tuple[str, str]] = ...,
+            default: Optional[Callable[..., Any]] = ...
+        ) -> None: ...
+    else:
+        def __init__(
+            self,
+            skipkeys: bool = ...,
+            ensure_ascii: bool = ...,
+            check_circular: bool = ...,
+            allow_nan: bool = ...,
+            sort_keys: bool = ...,
+            indent: Optional[int] = ...,
+            separators: Optional[Tuple[str, str]] = ...,
+            default: Optional[Callable[..., Any]] = ...,
+        ) -> None: ...
     def default(self, o: Any) -> Any: ...
     def encode(self, o: Any) -> str: ...
     def iterencode(self, o: Any, _one_shot: bool = ...) -> Iterator[str]: ...