diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index faacb44..9b72908 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -76,6 +76,7 @@
 int Py_InspectFlag; /* Needed to determine whether to exit at SystemError */
 int Py_NoSiteFlag; /* Suppress 'import site' */
 int Py_BytesWarningFlag; /* Warn on str(bytes) and str(buffer) */
+int Py_DontWriteBytecodeFlag; /* Suppress writing bytecode files (*.py[co]) */
 int Py_UseClassExceptionsFlag = 1; /* Needed by bltinmodule.c: deprecated */
 int Py_FrozenFlag; /* Needed by getpath.c */
 int Py_IgnoreEnvironmentFlag; /* e.g. PYTHONPATH, PYTHONHOME */
@@ -176,6 +177,8 @@
 		Py_VerboseFlag = add_flag(Py_VerboseFlag, p);
 	if ((p = Py_GETENV("PYTHONOPTIMIZE")) && *p != '\0')
 		Py_OptimizeFlag = add_flag(Py_OptimizeFlag, p);
+	if ((p = Py_GETENV("PYTHONDONTWRITEBYTECODE")) && *p != '\0')
+		Py_DontWriteBytecodeFlag = add_flag(Py_DontWriteBytecodeFlag, p);
 
 	interp = PyInterpreterState_New();
 	if (interp == NULL)