diff --git a/libc/include/signal.h b/libc/include/signal.h
index 29bef57..267f3e6 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -66,6 +66,8 @@
 typedef __sighandler_t sig_t; /* BSD compatibility. */
 typedef __sighandler_t sighandler_t; /* glibc compatibility. */
 
+#define si_timerid si_tid /* glibc compatibility. */
+
 #if defined(__LP64__)
 
 struct sigaction {