diff --git a/stdlib/2/subprocess.pyi b/stdlib/2/subprocess.pyi
index 125efb689..448df12f1 100644
--- a/stdlib/2/subprocess.pyi
+++ b/stdlib/2/subprocess.pyi
@@ -7,6 +7,7 @@ from typing import Sequence, Any, AnyStr, Mapping, Callable, Tuple, IO, Union, O
 _FILE = Union[int, IO[Any]]
 _TXT = Union[bytes, Text]
 _CMD = Union[_TXT, Sequence[_TXT]]
+_ENV = Union[Mapping[bytes, _TXT], Mapping[Text, _TXT]]
 
 # Same args as Popen.__init__
 def call(args: _CMD,
@@ -19,7 +20,7 @@ def call(args: _CMD,
          close_fds: bool = ...,
          shell: bool = ...,
          cwd: _TXT = ...,
-         env: Mapping[_TXT, _TXT] = ...,
+         env: _ENV = ...,
          universal_newlines: bool = ...,
          startupinfo: Any = ...,
          creationflags: int = ...) -> int: ...
@@ -34,7 +35,7 @@ def check_call(args: _CMD,
                close_fds: bool = ...,
                shell: bool = ...,
                cwd: _TXT = ...,
-               env: Mapping[_TXT, _TXT] = ...,
+               env: _ENV = ...,
                universal_newlines: bool = ...,
                startupinfo: Any = ...,
                creationflags: int = ...) -> int: ...
@@ -49,7 +50,7 @@ def check_output(args: _CMD,
                  close_fds: bool = ...,
                  shell: bool = ...,
                  cwd: _TXT = ...,
-                 env: Mapping[_TXT, _TXT] = ...,
+                 env: _ENV = ...,
                  universal_newlines: bool = ...,
                  startupinfo: Any = ...,
                  creationflags: int = ...) -> bytes: ...
@@ -87,7 +88,7 @@ class Popen:
                  close_fds: bool = ...,
                  shell: bool = ...,
                  cwd: Optional[_TXT] = ...,
-                 env: Optional[Mapping[_TXT, _TXT]] = ...,
+                 env: Optional[_ENV] = ...,
                  universal_newlines: bool = ...,
                  startupinfo: Optional[Any] = ...,
                  creationflags: int = ...) -> None: ...
diff --git a/stdlib/3/subprocess.pyi b/stdlib/3/subprocess.pyi
index 4d2fcae72..80761f4e7 100644
--- a/stdlib/3/subprocess.pyi
+++ b/stdlib/3/subprocess.pyi
@@ -8,6 +8,7 @@ from types import TracebackType
 _FILE = Union[int, IO[Any]]
 _TXT = Union[bytes, Text]
 _CMD = Union[_TXT, Sequence[_TXT]]
+_ENV = Union[Mapping[bytes, _TXT], Mapping[Text, _TXT]]
 
 if sys.version_info >= (3, 5):
     class CompletedProcess:
@@ -38,7 +39,7 @@ if sys.version_info >= (3, 5):
                 close_fds: bool = ...,
                 shell: bool = ...,
                 cwd: _TXT = ...,
-                env: Mapping[_TXT, _TXT] = ...,
+                env: _ENV = ...,
                 universal_newlines: bool = ...,
                 startupinfo: Any = ...,
                 creationflags: int = ...,
@@ -62,7 +63,7 @@ if sys.version_info >= (3, 5):
                 close_fds: bool = ...,
                 shell: bool = ...,
                 cwd: _TXT = ...,
-                env: Mapping[_TXT, _TXT] = ...,
+                env: _ENV = ...,
                 universal_newlines: bool = ...,
                 startupinfo: Any = ...,
                 creationflags: int = ...,
@@ -83,7 +84,7 @@ if sys.version_info >= (3, 3):
              close_fds: bool = ...,
              shell: bool = ...,
              cwd: _TXT = ...,
-             env: Mapping[_TXT, _TXT] = ...,
+             env: _ENV = ...,
              universal_newlines: bool = ...,
              startupinfo: Any = ...,
              creationflags: int = ...,
@@ -102,7 +103,7 @@ else:
              close_fds: bool = ...,
              shell: bool = ...,
              cwd: _TXT = ...,
-             env: Mapping[_TXT, _TXT] = ...,
+             env: _ENV = ...,
              universal_newlines: bool = ...,
              startupinfo: Any = ...,
              creationflags: int = ...,
@@ -123,7 +124,7 @@ if sys.version_info >= (3, 3):
                    close_fds: bool = ...,
                    shell: bool = ...,
                    cwd: _TXT = ...,
-                   env: Mapping[_TXT, _TXT] = ...,
+                   env: _ENV = ...,
                    universal_newlines: bool = ...,
                    startupinfo: Any = ...,
                    creationflags: int = ...,
@@ -142,7 +143,7 @@ else:
                    close_fds: bool = ...,
                    shell: bool = ...,
                    cwd: _TXT = ...,
-                   env: Mapping[_TXT, _TXT] = ...,
+                   env: _ENV = ...,
                    universal_newlines: bool = ...,
                    startupinfo: Any = ...,
                    creationflags: int = ...,
@@ -161,7 +162,7 @@ if sys.version_info >= (3, 4):
                      close_fds: bool = ...,
                      shell: bool = ...,
                      cwd: _TXT = ...,
-                     env: Mapping[_TXT, _TXT] = ...,
+                     env: _ENV = ...,
                      universal_newlines: bool = ...,
                      startupinfo: Any = ...,
                      creationflags: int = ...,
@@ -182,7 +183,7 @@ elif sys.version_info >= (3, 3):
                      close_fds: bool = ...,
                      shell: bool = ...,
                      cwd: _TXT = ...,
-                     env: Mapping[_TXT, _TXT] = ...,
+                     env: _ENV = ...,
                      universal_newlines: bool = ...,
                      startupinfo: Any = ...,
                      creationflags: int = ...,
@@ -202,7 +203,7 @@ else:
                      close_fds: bool = ...,
                      shell: bool = ...,
                      cwd: _TXT = ...,
-                     env: Mapping[_TXT, _TXT] = ...,
+                     env: _ENV = ...,
                      universal_newlines: bool = ...,
                      startupinfo: Any = ...,
                      creationflags: int = ...,
@@ -258,7 +259,7 @@ class Popen:
                      close_fds: bool = ...,
                      shell: bool = ...,
                      cwd: Optional[_TXT] = ...,
-                     env: Optional[Mapping[_TXT, _TXT]] = ...,
+                     env: Optional[_ENV] = ...,
                      universal_newlines: bool = ...,
                      startupinfo: Optional[Any] = ...,
                      creationflags: int = ...,
@@ -279,7 +280,7 @@ class Popen:
                      close_fds: bool = ...,
                      shell: bool = ...,
                      cwd: Optional[_TXT] = ...,
-                     env: Optional[Mapping[_TXT, _TXT]] = ...,
+                     env: Optional[_ENV] = ...,
                      universal_newlines: bool = ...,
                      startupinfo: Optional[Any] = ...,
                      creationflags: int = ...,