diff --git a/stdlib/3/subprocess.pyi b/stdlib/3/subprocess.pyi
index f41a71e5f..b9d7108a9 100644
--- a/stdlib/3/subprocess.pyi
+++ b/stdlib/3/subprocess.pyi
@@ -54,7 +54,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -82,7 +82,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -110,7 +110,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -138,7 +138,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -167,7 +167,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -195,7 +195,7 @@ if sys.version_info >= (3, 7):
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -226,7 +226,7 @@ else:
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -252,7 +252,7 @@ else:
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -278,7 +278,7 @@ else:
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -305,7 +305,7 @@ else:
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -331,7 +331,7 @@ else:
         stdin: _FILE = ...,
         stdout: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -358,7 +358,7 @@ def call(
     stdin: _FILE = ...,
     stdout: _FILE = ...,
     stderr: _FILE = ...,
-    preexec_fn: Callable[[], Any] = ...,
+    preexec_fn: Optional[Callable[[], Any]] = ...,
     close_fds: bool = ...,
     shell: bool = ...,
     cwd: Optional[AnyPath] = ...,
@@ -381,7 +381,7 @@ def check_call(
     stdin: _FILE = ...,
     stdout: _FILE = ...,
     stderr: _FILE = ...,
-    preexec_fn: Callable[[], Any] = ...,
+    preexec_fn: Optional[Callable[[], Any]] = ...,
     close_fds: bool = ...,
     shell: bool = ...,
     cwd: Optional[AnyPath] = ...,
@@ -404,7 +404,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -429,7 +429,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -454,7 +454,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -479,7 +479,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -505,7 +505,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -530,7 +530,7 @@ if sys.version_info >= (3, 7):
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -557,7 +557,7 @@ else:
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -581,7 +581,7 @@ else:
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -605,7 +605,7 @@ else:
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -629,7 +629,7 @@ else:
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,
@@ -653,7 +653,7 @@ else:
         executable: Optional[AnyPath] = ...,
         stdin: _FILE = ...,
         stderr: _FILE = ...,
-        preexec_fn: Callable[[], Any] = ...,
+        preexec_fn: Optional[Callable[[], Any]] = ...,
         close_fds: bool = ...,
         shell: bool = ...,
         cwd: Optional[AnyPath] = ...,