diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index 49f943a..346901a 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -94,16 +94,17 @@
 typedef long pthread_rwlockattr_t;
 
 typedef struct {
-  pthread_mutex_t lock;
-  pthread_cond_t cond;
-  int numLocks;
-  int writerThreadId;
-  int pendingReaders;
-  int pendingWriters;
-  void* __reserved[4];
+  pthread_mutex_t __unused_lock;
+  pthread_cond_t __unused_cond;
+  volatile int32_t state; // 0=unlock, -1=writer lock, +n=reader lock
+  volatile int32_t writerThreadId;
+  volatile int32_t pendingReaders;
+  volatile int32_t pendingWriters;
+  int32_t attr;
+  void* __reserved[3];
 } pthread_rwlock_t;
 
-#define PTHREAD_RWLOCK_INITIALIZER  { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0, 0, 0, { NULL, NULL, NULL, NULL } }
+#define PTHREAD_RWLOCK_INITIALIZER  { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0, 0, 0, 0, 0, { NULL, NULL, NULL } }
 
 typedef int pthread_key_t;
 typedef long pthread_t;