diff --git a/libc/intrin/pthreadlock.c b/libc/intrin/pthreadlock.c
index 68d55325a..3fd1d564a 100644
--- a/libc/intrin/pthreadlock.c
+++ b/libc/intrin/pthreadlock.c
@@ -20,6 +20,10 @@
 
 pthread_spinlock_t _pthread_lock_obj;
 
+void _pthread_init(void) {
+  (void)pthread_spin_init(&_pthread_lock_obj, 0);
+}
+
 void _pthread_lock(void) {
   pthread_spin_lock(&_pthread_lock_obj);
 }
diff --git a/libc/proc/fork.c b/libc/proc/fork.c
index aa437dc6d..68f020fe1 100644
--- a/libc/proc/fork.c
+++ b/libc/proc/fork.c
@@ -46,6 +46,7 @@ static void _onfork_prepare(void) {
   if (_weaken(_pthread_onfork_prepare)) {
     _weaken(_pthread_onfork_prepare)();
   }
+  _pthread_lock();
   __fds_lock();
   __mmi_lock();
 }
@@ -53,11 +54,26 @@ static void _onfork_prepare(void) {
 static void _onfork_parent(void) {
   __mmi_unlock();
   __fds_unlock();
+  _pthread_unlock();
   if (_weaken(_pthread_onfork_parent)) {
     _weaken(_pthread_onfork_parent)();
   }
 }
 
+static void _onfork_child(void) {
+  pthread_mutexattr_t attr;
+  pthread_mutexattr_init(&attr);
+  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+  extern pthread_mutex_t __mmi_lock_obj;
+  pthread_mutex_init(&__mmi_lock_obj, &attr);
+  pthread_mutex_init(&__fds_lock_obj, &attr);
+  pthread_mutexattr_destroy(&attr);
+  _pthread_init();
+  if (_weaken(_pthread_onfork_child)) {
+    _weaken(_pthread_onfork_child)();
+  }
+}
+
 int _fork(uint32_t dwCreationFlags) {
   struct Dll *e;
   int ax, dx, tid, parent;
@@ -117,8 +133,8 @@ int _fork(uint32_t dwCreationFlags) {
     atomic_store_explicit(&pt->pt_canceled, false, memory_order_relaxed);
 
     // run user fork callbacks
-    if (__threaded && _weaken(_pthread_onfork_child)) {
-      _weaken(_pthread_onfork_child)();
+    if (__threaded) {
+      _onfork_child();
     }
     STRACE("fork() → 0 (child of %d)", parent);
   } else {
diff --git a/libc/thread/posixthread.internal.h b/libc/thread/posixthread.internal.h
index cacd9e344..b0d56e94c 100644
--- a/libc/thread/posixthread.internal.h
+++ b/libc/thread/posixthread.internal.h
@@ -105,6 +105,7 @@ intptr_t _pthread_syshand(struct PosixThread *) libcesque;
 long _pthread_cancel_ack(void) libcesque;
 void _pthread_decimate(void) libcesque;
 void _pthread_free(struct PosixThread *, bool) libcesque;
+void _pthread_init(void) libcesque;
 void _pthread_lock(void) libcesque;
 void _pthread_onfork_child(void) libcesque;
 void _pthread_onfork_parent(void) libcesque;
diff --git a/libc/thread/pthread_atfork.c b/libc/thread/pthread_atfork.c
index c20ec1859..fd5cfa34a 100644
--- a/libc/thread/pthread_atfork.c
+++ b/libc/thread/pthread_atfork.c
@@ -46,8 +46,6 @@ static struct AtForks {
   atomic_int allocated;
 } _atforks;
 
-extern pthread_spinlock_t _pthread_lock_obj;
-
 static void _pthread_onfork(int i) {
   struct AtFork *a;
   unassert(0 <= i && i <= 2);
@@ -64,23 +62,13 @@ static void _pthread_onfork(int i) {
 
 void _pthread_onfork_prepare(void) {
   _pthread_onfork(0);
-  _pthread_lock();
 }
 
 void _pthread_onfork_parent(void) {
-  _pthread_unlock();
   _pthread_onfork(1);
 }
 
 void _pthread_onfork_child(void) {
-  pthread_mutexattr_t attr;
-  pthread_mutexattr_init(&attr);
-  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
-  extern pthread_mutex_t __mmi_lock_obj;
-  pthread_mutex_init(&__mmi_lock_obj, &attr);
-  pthread_mutex_init(&__fds_lock_obj, &attr);
-  pthread_mutexattr_destroy(&attr);
-  (void)pthread_spin_init(&_pthread_lock_obj, 0);
   _pthread_onfork(2);
 }