diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index b0e7822..de5c2bb 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -202,6 +202,7 @@
 int              poll (struct pollfd *, unsigned int, long);
 int              __set_tls (void*);
 int              cacheflush (long start, long end, long flags);
+int              eventfd (int count, int flags);
 #ifdef __cplusplus
 }
 #endif