diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 1cebf6b24a6..868f2798394 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -682,7 +682,6 @@ class ProcessTestCase(BaseTestCase):
             # on adding even when the environment in exec is empty.
             # Gentoo sandboxes also force LD_PRELOAD and SANDBOX_* to exist.
             return ('VERSIONER' in n or '__CF' in n or  # MacOS
-                    '__PYVENV_LAUNCHER__' in n or # MacOS framework build
                     n == 'LD_PRELOAD' or n.startswith('SANDBOX') or # Gentoo
                     n == 'LC_CTYPE') # Locale coercion triggered
 
diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index a3b78c4e44e..b2794cd992a 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -391,6 +391,18 @@ class BasicTest(BaseTest):
         self.assertEqual(err, "".encode())
 
 
+    @unittest.skipUnless(sys.platform == 'darwin', 'only relevant on macOS')
+    def test_macos_env(self):
+        rmtree(self.env_dir)
+        builder = venv.EnvBuilder()
+        builder.create(self.env_dir)
+
+        envpy = os.path.join(os.path.realpath(self.env_dir),
+                             self.bindir, self.exe)
+        out, err = check_output([envpy, '-c',
+            'import os; print("__PYVENV_LAUNCHER__" in os.environ)'])
+        self.assertEqual(out.strip(), 'False'.encode())
+
 @requireVenvCreate
 class EnsurePipTest(BaseTest):
     """Test venv module installation of pip."""
diff --git a/Mac/Tools/pythonw.c b/Mac/Tools/pythonw.c
index 1d2db383f94..c8bd3ba8d68 100644
--- a/Mac/Tools/pythonw.c
+++ b/Mac/Tools/pythonw.c
@@ -196,6 +196,15 @@ main(int argc, char **argv) {
             }
         }
 
+        /*
+         * The environment variable is used to pass the value of real_path
+         * to the actual python interpreter, and is read by code in
+         * Python/coreconfig.c.
+         *
+         * This way the real interpreter knows how the user invoked the
+         * interpreter and can behave as if this launcher is the real
+         * interpreter (looking for pyvenv configuration, ...)
+         */
         setenv("__PYVENV_LAUNCHER__", real_path, 1);
     }
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-09-23-16-32-58.bpo-22490.8e0YDf.rst b/Misc/NEWS.d/next/Core and Builtins/2018-09-23-16-32-58.bpo-22490.8e0YDf.rst
new file mode 100644
index 00000000000..a281f024249
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-09-23-16-32-58.bpo-22490.8e0YDf.rst	
@@ -0,0 +1,2 @@
+Don't leak environment variable ``__PYVENV_LAUNCHER__`` into the interpreter
+session on macOS.
diff --git a/Python/initconfig.c b/Python/initconfig.c
index 19070d2a3fa..7bad36ef17b 100644
--- a/Python/initconfig.c
+++ b/Python/initconfig.c
@@ -1139,6 +1139,17 @@ config_init_program_name(PyConfig *config)
             if (_PyStatus_EXCEPTION(status)) {
                 return status;
             }
+
+            /*
+             * This environment variable is used to communicate between
+             * the stub launcher and the real interpreter and isn't needed
+             * beyond this point.
+             *
+             * Clean up to avoid problems when launching other programs
+             * later on.
+             */
+            (void)unsetenv("__PYVENV_LAUNCHER__");
+
             return _PyStatus_OK();
         }
     }