diff --git a/stdlib/3/typing.pyi b/stdlib/3/typing.pyi
index 6c4dcc25302e..930d76213a00 100644
--- a/stdlib/3/typing.pyi
+++ b/stdlib/3/typing.pyi
@@ -506,7 +506,7 @@ class IO(Iterator[AnyStr], Generic[AnyStr]):
 class BinaryIO(IO[bytes]):
     # TODO readinto
     # TODO read1?
-    # TODO peek?
+    def peek(self, n: int = ...) -> bytes: ...
     @overload
     @abstractmethod
     def write(self, s: bytearray) -> int: ...
diff --git a/tests/stubtest_whitelists/py35.txt b/tests/stubtest_whitelists/py35.txt
index 4a5b6e5758d2..a0a3ed36c391 100644
--- a/tests/stubtest_whitelists/py35.txt
+++ b/tests/stubtest_whitelists/py35.txt
@@ -53,6 +53,7 @@ sre_compile.dis
 subprocess.check_output
 tracemalloc.Filter.__init__
 typing.AbstractSet.isdisjoint
+typing.BinaryIO.peek
 typing.Coroutine.cr_await
 typing.Coroutine.cr_code
 typing.Coroutine.cr_frame
diff --git a/tests/stubtest_whitelists/py36.txt b/tests/stubtest_whitelists/py36.txt
index a80097857f90..4788afc09f61 100644
--- a/tests/stubtest_whitelists/py36.txt
+++ b/tests/stubtest_whitelists/py36.txt
@@ -53,6 +53,7 @@ typing.AsyncGenerator.ag_await
 typing.AsyncGenerator.ag_code
 typing.AsyncGenerator.ag_frame
 typing.AsyncGenerator.ag_running
+typing.BinaryIO.peek
 typing.Coroutine.cr_await
 typing.Coroutine.cr_code
 typing.Coroutine.cr_frame
diff --git a/tests/stubtest_whitelists/py37.txt b/tests/stubtest_whitelists/py37.txt
index 3da982868a7b..725c48b6bf40 100644
--- a/tests/stubtest_whitelists/py37.txt
+++ b/tests/stubtest_whitelists/py37.txt
@@ -64,6 +64,7 @@ tracemalloc.Traceback.format
 types.ClassMethodDescriptorType.__get__
 types.MethodDescriptorType.__get__
 types.WrapperDescriptorType.__get__
+typing.BinaryIO.peek
 typing.runtime_checkable
 unittest.async_case
 urllib.parse.parse_qs
diff --git a/tests/stubtest_whitelists/py38.txt b/tests/stubtest_whitelists/py38.txt
index 7dd11a8e50cb..fb07ebd9f070 100644
--- a/tests/stubtest_whitelists/py38.txt
+++ b/tests/stubtest_whitelists/py38.txt
@@ -146,6 +146,7 @@ types.ClassMethodDescriptorType.__get__
 types.CodeType.replace
 types.MethodDescriptorType.__get__
 types.WrapperDescriptorType.__get__
+typing.BinaryIO.peek
 unittest.TestCase.addCleanup
 unittest.case.TestCase.addCleanup
 unittest.doModuleCleanups