diff --git a/plugins/rack/rack_plugin.c b/plugins/rack/rack_plugin.c
index 74de0e7b..2b2cb0c5 100644
--- a/plugins/rack/rack_plugin.c
+++ b/plugins/rack/rack_plugin.c
@@ -259,7 +259,7 @@ int uwsgi_request(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req) {
                 return -1;
         }
 
-        if (uwsgi_parse_vars(uwsgi, wsgi_req)) {
+        if (uwsgi_parse_vars(wsgi_req)) {
                 uwsgi_log("Invalid RACK request. skip.\n");
                 return -1;
         }
diff --git a/plugins/rack/uwsgiplugin.py b/plugins/rack/uwsgiplugin.py
index 5ba1c251..c9ae8636 100644
--- a/plugins/rack/uwsgiplugin.py
+++ b/plugins/rack/uwsgiplugin.py
@@ -1,5 +1,6 @@
 import os,sys
 
 NAME='rack'
-CFLAGS = '-I' + os.popen("ruby -e \"require 'mkmf';print Config::CONFIG['archdir']\"").read().rstrip()
-LDFLAGS = '-l' + os.popen("ruby -e \"require 'mkmf';print CONFIG['RUBY_SO_NAME']\"").read().rstrip()
+#CFLAGS = '-I' + os.popen("/Users/roberto/RUBY/bin/ruby -e \"require 'mkmf';print Config::CONFIG['archdir']\"").read().rstrip()
+CFLAGS = '-I/Users/roberto/RUBY//include/ruby-1.9.1 -DHAVE_STRUCT_TIMESPEC -DHAVE_STRUCT_TIMEZONE'
+LDFLAGS = '-l' + os.popen("/Users/roberto/RUBY/bin/ruby -e \"require 'mkmf';print CONFIG['RUBY_SO_NAME']\"").read().rstrip()
diff --git a/pyloader.c b/pyloader.c
index 9c998d38..ab1b0cad 100644
--- a/pyloader.c
+++ b/pyloader.c
@@ -34,6 +34,10 @@ int init_uwsgi_app(int loader, void *arg1, struct wsgi_request *wsgi_req, int ne
 
 	struct uwsgi_app *wi;
 
+	if (uwsgi.threads > 1) {
+		pthread_mutex_lock(&uwsgi.lock_pyloaders);
+	}
+
 	if (wsgi_req->script_name_len == 0) {
 		wsgi_req->script_name = "";
 		if (!uwsgi.vhost) id = 0;
@@ -55,6 +59,9 @@ int init_uwsgi_app(int loader, void *arg1, struct wsgi_request *wsgi_req, int ne
 	if (uwsgi_get_app_id(mountpoint, strlen(mountpoint)) != -1) {
 		uwsgi_log( "mountpoint %.*s already configured. skip.\n", strlen(mountpoint), mountpoint);
 		free(mountpoint);
+		if (uwsgi.threads > 1) {
+			pthread_mutex_unlock(&uwsgi.lock_pyloaders);
+		}
 		return -1;
 	}
 
@@ -251,6 +258,9 @@ int init_uwsgi_app(int loader, void *arg1, struct wsgi_request *wsgi_req, int ne
 	}
 
 	uwsgi_log("\n");
+	if (uwsgi.threads > 1) {
+		pthread_mutex_unlock(&uwsgi.lock_pyloaders);
+	}
 
 	return id;
 
@@ -266,6 +276,9 @@ doh:
 			PyThreadState_Swap(uwsgi.main_thread);
 		}
 	}
+	if (uwsgi.threads > 1) {
+		pthread_mutex_unlock(&uwsgi.lock_pyloaders);
+	}
 	return -1;
 }
 
diff --git a/uwsgi.c b/uwsgi.c
index 7ad351ac..223ece90 100644
--- a/uwsgi.c
+++ b/uwsgi.c
@@ -969,6 +969,8 @@ int main(int argc, char *argv[], char *envp[]) {
                         exit(1);
                 }
 		pthread_setspecific(uwsgi.ut_save_key, (void *) PyThreadState_Get());
+		// initialize the mutexes
+		pthread_mutex_init(&uwsgi.lock_pyloaders, NULL);
 		uwsgi.gil_get = gil_real_get; 
 		uwsgi.gil_release = gil_real_release; 
 		uwsgi.current_wsgi_req = threaded_current_wsgi_req;
diff --git a/uwsgi.h b/uwsgi.h
index 26846582..3036f3e3 100644
--- a/uwsgi.h
+++ b/uwsgi.h
@@ -807,6 +807,10 @@ struct uwsgi_server {
 	struct wsgi_request* (*current_wsgi_req)(void);
 
 	int close_on_exec;
+
+#ifdef UWSGI_THREADING
+	pthread_mutex_t lock_pyloaders;
+#endif
 };
 
 struct uwsgi_cluster_node {