diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 80002e9..8fbaf22 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -38,6 +38,9 @@
 /* Has the thread been joined by another thread? */
 #define PTHREAD_ATTR_FLAG_JOINED 0x00000002
 
+/* Did the thread exit without freeing pthread_internal_t? */
+#define PTHREAD_ATTR_FLAG_ZOMBIE 0x00000004
+
 /* Is this the main thread? */
 #define PTHREAD_ATTR_FLAG_MAIN_THREAD 0x80000000