diff --git a/ini.c b/ini.c
index 63eccef5..6f6a4bd0 100644
--- a/ini.c
+++ b/ini.c
@@ -136,6 +136,11 @@ void uwsgi_ini_config(char *file, char *magic_table[]) {
 								add_exported_option(0, (char *)key);
 							}
 							else {
+								if (aopt->has_arg == optional_argument) {
+									if (!strcmp("true", val)) {
+										val = NULL;
+									}
+								}
 								manage_opt(aopt->val, val);
 							}
 						}
diff --git a/plugins/python/pyloader.c b/plugins/python/pyloader.c
index 11ec3452..a62ec161 100644
--- a/plugins/python/pyloader.c
+++ b/plugins/python/pyloader.c
@@ -9,6 +9,8 @@
 extern struct uwsgi_server uwsgi;
 extern struct uwsgi_python up;
 
+extern char **environ;
+
 #ifdef UWSGI_SENDFILE
 PyMethodDef uwsgi_sendfile_method[] = {{"uwsgi_sendfile", py_uwsgi_sendfile, METH_VARARGS, ""}};
 #endif
@@ -79,6 +81,51 @@ int init_uwsgi_app(int loader, void *arg1, struct wsgi_request *wsgi_req, PyThre
 
 	// Initialize a new environment for the new interpreter
 
+	// reload "os" environ to allow dynamic setenv()
+	if (up.reload_os_env) {
+
+                char **e, *p;
+                PyObject *k, *env_value;
+
+        	PyObject *os_module = PyImport_ImportModule("os");
+        	if (os_module) {
+                	PyObject *os_module_dict = PyModule_GetDict(os_module);
+                	PyObject *py_environ = PyDict_GetItemString(os_module_dict, "environ");
+			if (py_environ) {
+                		for (e = environ; *e != NULL; e++) {
+                        		p = strchr(*e, '=');
+                        		if (p == NULL) continue;
+
+					k = PyString_FromStringAndSize(*e, (int)(p-*e));
+					if (k == NULL) {
+                                		PyErr_Print();
+                                		continue;
+					}
+
+                        		env_value = PyString_FromString(p+1);
+                        		if (env_value == NULL) {
+                                		PyErr_Print();
+						Py_DECREF(k);
+                                		continue;
+                        		}
+	
+					uwsgi_log("%s = %s\n", PyString_AsString(k), PyString_AsString(env_value));
+
+                        		if (PyObject_SetItem(py_environ, k, env_value)) {
+						uwsgi_log("cazzo\n");
+                                		PyErr_Print();
+                        		}
+
+                        		Py_DECREF(k);
+                        		Py_DECREF(env_value);
+
+                	}
+
+		}
+        	}
+	}
+
+
 	if (interpreter == NULL && id) {
 		wi->interpreter = Py_NewInterpreter();
 		if (!wi->interpreter) {
diff --git a/plugins/python/python_plugin.c b/plugins/python/python_plugin.c
index 605adc52..8e4fddae 100644
--- a/plugins/python/python_plugin.c
+++ b/plugins/python/python_plugin.c
@@ -26,6 +26,7 @@ struct option uwsgi_python_options[] = {
 	{"catch-exceptions", no_argument, &up.catch_exceptions, 1},
 	{"ignore-script-name", no_argument, &up.ignore_script_name, 1},
 	{"pep3333-input", no_argument, &up.pep3333_input, 1},
+	{"reload-os-env", no_argument, &up.reload_os_env, 1},
 	{"no-site", no_argument, &Py_NoSiteFlag, 1},
 
 	{0, 0, 0, 0},
diff --git a/plugins/python/pyutils.c b/plugins/python/pyutils.c
index 21a188a5..c1fb2e17 100644
--- a/plugins/python/pyutils.c
+++ b/plugins/python/pyutils.c
@@ -96,4 +96,6 @@ void init_pyargv() {
 		}
 
 		PySys_SetArgv(up.argc, up.py_argv);
-	}
+
+
+}
diff --git a/plugins/python/uwsgi_python.h b/plugins/python/uwsgi_python.h
index 5bf263d7..ac5d37ad 100644
--- a/plugins/python/uwsgi_python.h
+++ b/plugins/python/uwsgi_python.h
@@ -11,6 +11,7 @@
 #define LONG_ARGS_PASTE                 LONG_ARGS_PYTHON_BASE + 2
 #define LONG_ARGS_PYARGV                LONG_ARGS_PYTHON_BASE + 3
 #define LONG_ARGS_PYMODULE_ALIAS        LONG_ARGS_PYTHON_BASE + 4
+#define LONG_ARGS_RELOAD_OS_ENV		LONG_ARGS_PYTHON_BASE + 5
 
 #ifdef UWSGI_STACKLESS
 #include <stackless_api.h>
@@ -134,6 +135,8 @@ struct uwsgi_python {
 	int pep3333_input;
 
 	void (*extension)(void);
+
+	int reload_os_env;
 };
 
 
diff --git a/protocol.c b/protocol.c
index 14afc9aa..628c1a22 100644
--- a/protocol.c
+++ b/protocol.c
@@ -512,6 +512,17 @@ int uwsgi_parse_vars(struct wsgi_request *wsgi_req) {
 							wsgi_req->chdir = ptrbuf;
 							wsgi_req->chdir_len = strsize;
 						}
+						else if (!uwsgi_strncmp("UWSGI_SETENV", 12, wsgi_req->hvec[wsgi_req->var_cnt].iov_base, wsgi_req->hvec[wsgi_req->var_cnt].iov_len)) {
+							char *env_value = memchr(ptrbuf, '=', strsize);
+							if (env_value) {
+								env_value[0] = 0;
+								env_value = uwsgi_concat2n(env_value+1, strsize-((env_value+1)-ptrbuf), "", 0);
+								if (setenv(ptrbuf, env_value, 1)) {
+									uwsgi_error("setenv()");
+								}
+								free(env_value);
+							}
+						}
 						else if (!uwsgi_strncmp("SERVER_NAME", 11, wsgi_req->hvec[wsgi_req->var_cnt].iov_base, wsgi_req->hvec[wsgi_req->var_cnt].iov_len) && !uwsgi.vhost_host) {
 							wsgi_req->host = ptrbuf;
 							wsgi_req->host_len = strsize;
diff --git a/yaml.c b/yaml.c
index b94bcfc6..7459ea6c 100644
--- a/yaml.c
+++ b/yaml.c
@@ -181,6 +181,11 @@ void uwsgi_yaml_config(char *file, char *magic_table[]) {
 						add_exported_option(0, (char *)key);
 					}
 					else {
+						if (aopt->has_arg == optional_argument) {
+                                                        if (!strcmp("true", val)) {
+                                                        	val = NULL;
+                                                	}
+                                                }
 						manage_opt(aopt->val, val);
 					}
 				}