diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index c528105..206d5fd 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -39,6 +39,7 @@
 
 #include <async_safe/log.h>
 
+#include "private/ScopedRWLock.h"
 #include "private/bionic_constants.h"
 #include "private/bionic_defs.h"
 #include "private/bionic_globals.h"
@@ -357,6 +358,7 @@
   return nullptr;
 }
 
+pthread_rwlock_t g_thread_creation_lock = PTHREAD_RWLOCK_INITIALIZER;
 
 __BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
@@ -406,6 +408,8 @@
   tls = &tls_descriptor;
 #endif
 
+  ScopedReadLock locker(&g_thread_creation_lock);
+
   sigset64_t block_all_mask;
   sigfillset64(&block_all_mask);
   __rt_sigprocmask(SIG_SETMASK, &block_all_mask, &thread->start_mask, sizeof(thread->start_mask));