diff --git a/stdlib/2.7/subprocess.pyi b/stdlib/2.7/subprocess.pyi
index df8da0acd..f3b1eb4d5 100644
--- a/stdlib/2.7/subprocess.pyi
+++ b/stdlib/2.7/subprocess.pyi
@@ -72,17 +72,17 @@ class Popen:
     def __init__(self,
                  args: Union[str, Sequence[str]],
                  bufsize: int = ...,
-                 executable: str = ...,
-                 stdin: _FILE = ...,
-                 stdout: _FILE = ...,
-                 stderr: _FILE = ...,
-                 preexec_fn: Callable[[], Any] = ...,
+                 executable: Optional[str] = ...,
+                 stdin: Optional[_FILE] = ...,
+                 stdout: Optional[_FILE] = ...,
+                 stderr: Optional[_FILE] = ...,
+                 preexec_fn: Optional[Callable[[], Any]] = ...,
                  close_fds: bool = ...,
                  shell: bool = ...,
-                 cwd: str = ...,
-                 env: Mapping[str, str] = ...,
+                 cwd: Optional[str] = ...,
+                 env: Optional[Mapping[str, str]] = ...,
                  universal_newlines: bool = ...,
-                 startupinfo: Any = ...,
+                 startupinfo: Optional[Any] = ...,
                  creationflags: int = ...) -> None: ...
 
     def poll(self) -> int: ...
diff --git a/stdlib/3/subprocess.pyi b/stdlib/3/subprocess.pyi
index b1669771c..fd9e95b89 100644
--- a/stdlib/3/subprocess.pyi
+++ b/stdlib/3/subprocess.pyi
@@ -208,17 +208,17 @@ class Popen:
     def __init__(self,
                   args: Union[str, Sequence[str]],
                   bufsize: int = ...,
-                  executable: str = ...,
-                  stdin: Any = ...,
-                  stdout: Any = ...,
-                  stderr: Any = ...,
-                  preexec_fn: Callable[[], Any] = ...,
+                  executable: Optional[str] = ...,
+                  stdin: Optional[Any] = ...,
+                  stdout: Optional[Any] = ...,
+                  stderr: Optional[Any] = ...,
+                  preexec_fn: Optional[Callable[[], Any]] = ...,
                   close_fds: bool = ...,
                   shell: bool = ...,
-                  cwd: str = ...,
-                  env: Mapping[str, str] = ...,
+                  cwd: Optional[str] = ...,
+                  env: Optional[Mapping[str, str]] = ...,
                   universal_newlines: bool = ...,
-                  startupinfo: Any = ...,
+                  startupinfo: Optional[Any] = ...,
                   creationflags: int = ...,
                   restore_signals: bool = ...,
                   start_new_session: bool = ...,