diff --git a/sys/trace.h b/sys/trace.h
new file mode 100644
index 0000000..9c1c473
--- /dev/null
+++ b/sys/trace.h
@@ -0,0 +1,18 @@
+#ifndef LPC_TRACE_H_
+#define LPC_TRACE_H_
+
+/* Argument values for the trace() efun.
+ */
+
+#define TRACE_NOTHING       0  /* Stop tracing */
+
+#define TRACE_CALL          1  /* Trace all lfun calls */
+#define TRACE_CALL_OTHER    2  /* Trace inter-object calls */
+#define TRACE_RETURN        4  /* Trace function returns */
+#define TRACE_ARGS          8  /* Print function arguments and results */
+#define TRACE_EXEC         16  /* Trace all executed instructions */
+#define TRACE_HEART_BEAT   32  /* Trace heartbeat code */
+#define TRACE_APPLY        64  /* Trace (internal) applies */
+#define TRACE_OBJNAME     128  /* Print the object names */
+
+#endif /* LPC_TRACE_H_ */