Index: src/runtime/threading.m
==================================================================
--- src/runtime/threading.m
+++ src/runtime/threading.m
@@ -22,26 +22,23 @@
 #import "runtime.h"
 #import "runtime-private.h"
 #import "threading.h"
 
 static of_rmutex_t global_mutex;
-static bool global_mutex_init = false;
+static of_once_t once_control = OF_ONCE_INIT;
 
 static void
-objc_global_mutex_new(void)
+init(void)
 {
 	if (!of_rmutex_new(&global_mutex))
 		OBJC_ERROR("Failed to create global mutex!");
-
-	global_mutex_init = true;
 }
 
 void
 objc_global_mutex_lock(void)
 {
-	if (!global_mutex_init)
-		objc_global_mutex_new();
+	of_once(&once_control, init);
 
 	if (!of_rmutex_lock(&global_mutex))
 		OBJC_ERROR("Failed to lock global mutex!");
 }
 

Index: src/socket.m
==================================================================
--- src/socket.m
+++ src/socket.m
@@ -15,27 +15,40 @@
  */
 
 #include "config.h"
 
 #import "socket.h"
+#ifdef OF_HAVE_THREADS
+# include "threading.h"
 
+static of_once_t onceControl = OF_ONCE_INIT;
+#endif
 static bool initialized = false;
+
+static void
+init(void)
+{
+#if defined(_WIN32)
+	WSADATA wsa;
+
+	if (WSAStartup(MAKEWORD(2, 0), &wsa))
+		return;
+#elif defined(__wii__)
+	if (net_init() < 0)
+		return;
+#endif
+
+	initialized = true;
+}
 
 bool
 of_init_sockets()
 {
-	if (initialized)
-		return true;
-
-#ifdef _WIN32
-	WSADATA wsa;
-
-	if (WSAStartup(MAKEWORD(2, 0), &wsa))
-		return false;
-#elif defined(__wii__)
-	if (net_init() < 0)
-		return false;
+#ifdef OF_HAVE_THREADS
+	of_once(&onceControl, init);
+#else
+	if (!initialized)
+		init();
 #endif
 
-	initialized = true;
-	return true;
+	return initialized;
 }

Index: src/threading.h
==================================================================
--- src/threading.h
+++ src/threading.h
@@ -31,10 +31,12 @@
 # include <pthread.h>
 typedef pthread_t of_thread_t;
 typedef pthread_key_t of_tlskey_t;
 typedef pthread_mutex_t of_mutex_t;
 typedef pthread_cond_t of_condition_t;
+typedef pthread_once_t of_once_t;
+# define OF_ONCE_INIT PTHREAD_ONCE_INIT
 #elif defined(_WIN32)
 /*
  * winsock2.h needs to be included before windows.h. Not including it here
  * would make it impossible to use sockets after threading.h has been
  * imported.
@@ -48,10 +50,12 @@
 typedef CRITICAL_SECTION of_mutex_t;
 typedef struct {
 	HANDLE event;
 	int count;
 } of_condition_t;
+typedef volatile LONG of_once_t;
+# define OF_ONCE_INIT 0
 #else
 # error No threads available!
 #endif
 
 #if defined(OF_HAVE_ATOMIC_OPS)
@@ -148,10 +152,31 @@
 	ExitThread(0);
 #else
 # error of_thread_exit not implemented!
 #endif
 }
+
+static OF_INLINE void
+of_once(of_once_t *control, void (*func)(void))
+{
+#if defined(OF_HAVE_PTHREADS)
+	pthread_once(control, func);
+#elif defined(_WIN32)
+	switch (InterlockedCompareExchange(control, 1, 0)) {
+	case 0:
+		func();
+		InterlockedIncrement(control);
+		break;
+	case 1:
+		while (*control == 1)
+			Sleep(0);
+		break;
+	}
+#else
+# error of_once not implemented!
+#endif
+}
 
 static OF_INLINE bool
 of_mutex_new(of_mutex_t *mutex)
 {
 #if defined(OF_HAVE_PTHREADS)