+#ifdef USE_PTHREADS
+#if USE_REENTRANT
+#include <pthread.h>
+#define _nc_lock_mutex(name) pthread_mutex_lock(&_nc_globals.mutex_##name)
+#define _nc_unlock_mutex(name) pthread_mutex_unlock(&_nc_globals.mutex_##name)
+#else
+#error POSIX threads requires --enable-reentrant option
+#endif
+#else
+#define _nc_lock_mutex(name) /* nothing */
+#define _nc_unlock_mutex(name) /* nothing */
+#endif
+