diff --git a/Userland/Libraries/LibC/pthread.h b/Userland/Libraries/LibC/pthread.h
index 7129fbdde43650..1b1677fac62a0d 100644
--- a/Userland/Libraries/LibC/pthread.h
+++ b/Userland/Libraries/LibC/pthread.h
@@ -81,9 +81,10 @@ int pthread_setschedparam(pthread_t thread, int policy, const struct sched_param
         0, 0, CLOCK_MONOTONIC_COARSE \
     }
 
-// FIXME: Actually implement this!
 #define PTHREAD_RWLOCK_INITIALIZER \
-    NULL
+    {                              \
+        0                          \
+    }
 
 #define PTHREAD_KEYS_MAX 64
 #define PTHREAD_DESTRUCTOR_ITERATIONS 4