diff --git a/stdlib/2/random.pyi b/stdlib/2/random.pyi
index 3292db864..65d323db1 100644
--- a/stdlib/2/random.pyi
+++ b/stdlib/2/random.pyi
@@ -7,12 +7,14 @@
 # ----- random classes -----
 
 import _random
-from typing import (
-    Any, TypeVar, Sequence, List, Callable, AbstractSet, Union,
-    overload
-)
+from typing import AbstractSet, Any, Callable, Iterator, List, Protocol, Sequence, TypeVar, Union, overload
 
-_T = TypeVar('_T')
+_T = TypeVar("_T")
+_T_co = TypeVar('_T_co', covariant=True)
+
+class _Sampleable(Protocol[_T_co]):
+    def __iter__(self) -> Iterator[_T_co]: ...
+    def __len__(self) -> int: ...
 
 class Random(_random.Random):
     def __init__(self, x: object = ...) -> None: ...
@@ -28,7 +30,7 @@ class Random(_random.Random):
     def randint(self, a: int, b: int) -> int: ...
     def choice(self, seq: Sequence[_T]) -> _T: ...
     def shuffle(self, x: List[Any], random: Callable[[], None] = ...) -> None: ...
-    def sample(self, population: Union[Sequence[_T], AbstractSet[_T]], k: int) -> List[_T]: ...
+    def sample(self, population: _Sampleable[_T], k: int) -> List[_T]: ...
     def random(self) -> float: ...
     def uniform(self, a: float, b: float) -> float: ...
     def triangular(self, low: float = ..., high: float = ..., mode: float = ...) -> float: ...
@@ -59,7 +61,7 @@ def randrange(start: int, stop: int, step: int = ...) -> int: ...
 def randint(a: int, b: int) -> int: ...
 def choice(seq: Sequence[_T]) -> _T: ...
 def shuffle(x: List[Any], random: Callable[[], float] = ...) -> None: ...
-def sample(population: Union[Sequence[_T], AbstractSet[_T]], k: int) -> List[_T]: ...
+def sample(population: _Sampleable[_T], k: int) -> List[_T]: ...
 def random() -> float: ...
 def uniform(a: float, b: float) -> float: ...
 def triangular(low: float = ..., high: float = ...,