diff --git a/userspace/libraries/LibC/include/pthread.h b/userspace/libraries/LibC/include/pthread.h
index 8c512163..a66c8cff 100644
--- a/userspace/libraries/LibC/include/pthread.h
+++ b/userspace/libraries/LibC/include/pthread.h
@@ -53,6 +53,7 @@ struct uthread
 #define PTHREAD_MUTEX_NORMAL			2
 #define PTHREAD_MUTEX_RECURSIVE			3
 
+#define PTHREAD_SPIN_INITIALIZER   (pthread_spinlock_t)0
 #define PTHREAD_COND_INITIALIZER   (pthread_cond_t)0
 #define PTHREAD_MUTEX_INITIALIZER  (pthread_mutex_t){ { PTHREAD_MUTEX_DEFAULT, false }, 0, 0 }
 #define PTHREAD_RWLOCK_INITIALIZER (pthread_rwlock_t){ { false }, 0, 0 }