diff --git a/src/include/util.h b/src/include/util.h
index 7265cf1..d832956 100644
--- a/src/include/util.h
+++ b/src/include/util.h
@@ -1,6 +1,8 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#include <signal.h>
+
 // Most of this file is cursed printing macros for `ast_print()`. Do not attempt
 // to comprehend.
 
@@ -10,6 +12,9 @@
 // Get the length of an array.
 #define arrln(A) (sizeof(A)/sizeof(*A))
 
+// Trap GDB &c.
+#define TRAP() RAISE(SIGTRAP)
+
 #ifdef DBG // Debug macros
 
 // Log a message.