diff --git a/stdlib/2and3/traceback.pyi b/stdlib/2and3/traceback.pyi
index 2b83b5dcb..45108bf22 100644
--- a/stdlib/2and3/traceback.pyi
+++ b/stdlib/2and3/traceback.pyi
@@ -28,10 +28,17 @@ else:
                    file: Optional[IO[str]] = ...) -> None: ...
 def print_stack(f: Optional[FrameType] = ..., limit: Optional[int] = ...,
                 file: Optional[IO[str]] = ...) -> None: ...
-def extract_tb(tb: Optional[TracebackType], limit: Optional[int] = ...) -> List[_PT]: ...
-def extract_stack(f: Optional[FrameType] = ...,
-                  limit: Optional[int] = ...) -> List[_PT]: ...
-def format_list(extracted_list: List[_PT]) -> List[str]: ...
+
+if sys.version_info >= (3, 5):
+    def extract_tb(tb: Optional[TracebackType], limit: Optional[int] = ...) -> StackSummary: ...
+    def extract_stack(f: Optional[FrameType] = ...,
+                      limit: Optional[int] = ...) -> StackSummary: ...
+    def format_list(extracted_list: List[FrameSummary]) -> List[str]: ...
+else:
+    def extract_tb(tb: Optional[TracebackType], limit: Optional[int] = ...) -> List[_PT]: ...
+    def extract_stack(f: Optional[FrameType] = ...,
+                      limit: Optional[int] = ...) -> List[_PT]: ...
+    def format_list(extracted_list: List[_PT]) -> List[str]: ...
 def format_exception_only(etype: Type[BaseException],
                           value: BaseException) -> List[str]: ...
 if sys.version_info >= (3,):
@@ -82,7 +89,13 @@ if sys.version_info >= (3, 5):
 
 
 if sys.version_info >= (3, 5):
-    class StackSummary:
+    class FrameSummary:
+        def __init__(self, filename: str, lineno: int, name: str,
+                     lookup_line: bool = ...,
+                     locals: Optional[Mapping[str, str]] = ...,
+                     line: Optional[int] = ...) -> None: ...
+
+    class StackSummary(List[FrameSummary]):
         @classmethod
         def extract(cls,
                     frame_gen: Generator[Tuple[FrameType, int], None, None],
@@ -90,11 +103,3 @@ if sys.version_info >= (3, 5):
                     capture_locals: bool = ...) -> StackSummary: ...
         @classmethod
         def from_list(cls, a_list: List[_PT]) -> StackSummary: ...
-
-
-if sys.version_info >= (3, 5):
-    class FrameSummary:
-        def __init__(self, filename: str, lineno: int, name: str,
-                     lookup_line: bool = ...,
-                     locals: Optional[Mapping[str, str]] = ...,
-                     line: Optional[int] = ...) -> None: ...