diff --git a/libc/include/sys/procfs.h b/libc/include/sys/procfs.h
index 7ef5023..eff39e2 100644
--- a/libc/include/sys/procfs.h
+++ b/libc/include/sys/procfs.h
@@ -49,6 +49,14 @@
 typedef pid_t lwpid_t;
 typedef void* psaddr_t;
 
+struct elf_siginfo {
+  int si_signo;
+  int si_code;
+  int si_errno;
+};
+
+#define ELF_PRARGSZ 80
+
 __END_DECLS
 
 #endif /* _SYS_PROCFS_H_ */
diff --git a/libc/include/sys/user.h b/libc/include/sys/user.h
index f9ad956..ed3e10a 100644
--- a/libc/include/sys/user.h
+++ b/libc/include/sys/user.h
@@ -102,6 +102,10 @@
   int u_debugreg[8];
 };
 
+#define UPAGES 1
+#define HOST_TEXT_START_ADDR (u.start_code)
+#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * PAGE_SIZE)
+
 #elif defined(__x86_64__)
 
 struct user_fpregs_struct {