diff --git a/include/signal.h b/include/signal.h
index a4f85cca..5c48cb83 100644
--- a/include/signal.h
+++ b/include/signal.h
@@ -233,6 +233,7 @@ void (*sigset(int, void (*)(int)))(int);
 #define TRAP_TRACE 2
 #define TRAP_BRANCH 3
 #define TRAP_HWBKPT 4
+#define TRAP_UNK 5
 #define POLL_IN 1
 #define POLL_OUT 2
 #define POLL_MSG 3