diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index 63695d3..9e06afc 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -50,6 +50,8 @@
 
 extern "C" void ATTRIBUTES _thread_created_hook(pid_t thread_id);
 
+extern "C" int __set_tls(void* ptr);
+
 static const int kPthreadInitFailed = 1;
 
 static pthread_mutex_t gPthreadStackCreationLock = PTHREAD_MUTEX_INITIALIZER;