diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index eb2d169..33039b9 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -219,6 +219,41 @@
  */
 int pthread_mutex_lock_timeout_np(pthread_mutex_t *mutex, unsigned msecs);
 
+/* read-write lock support */
+
+typedef int pthread_rwlockattr_t;
+
+typedef struct {
+    pthread_mutex_t  lock;
+    pthread_cond_t   cond;
+    int              numLocks;
+    int              writerThreadId;
+    int              pendingReaders;
+    int              pendingWriters;
+    void*            reserved[4];  /* for future extensibility */
+} pthread_rwlock_t;
+
+#define PTHREAD_RWLOCK_INITIALIZER  { PTHREAD_MUTEX_INITIALIZER, 0, NULL, 0, 0 }
+
+int pthread_rwlockattr_init(pthread_rwlockattr_t *attr);
+int pthread_rwlockattr_destroy(pthread_rwlockattr_t *attr);
+int pthread_rwlockattr_setpshared(pthread_rwlockattr_t *attr, int  pshared);
+int pthread_rwlockattr_getpshared(pthread_rwlockattr_t *attr, int *pshared);
+
+int pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr);
+int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
+
+int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_timedrdlock(pthread_rwlock_t *rwlock, const struct timespec *abs_timeout);
+
+int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
+int pthread_rwlock_timedwrlock(pthread_rwlock_t *rwlock, const struct timespec *abs_timeout);
+
+int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
+
+
 int pthread_key_create(pthread_key_t *key, void (*destructor_function)(void *));
 int pthread_key_delete (pthread_key_t);
 int pthread_setspecific(pthread_key_t key, const void *value);