diff --git a/src/scenario.h b/src/scenario.h
index 0636ed6..d4a8943 100644
--- a/src/scenario.h
+++ b/src/scenario.h
@@ -101,11 +101,11 @@ static inline int sl_getPage(void) { return sl_page; }
 static inline int sl_getc(void) { return sl_sco[sl_index++]; }
 
 #define TRACE_UNIMPLEMENTED(fmt, ...) \
-	sys_message(2, "Unimplemented: " fmt "\n", ##__VA_ARGS__)
+	sys_message(2, "[UNIMPLEMENTED] " fmt "\n", ##__VA_ARGS__)
 
 #ifdef DEBUG
 #define TRACE(fmt, ...) \
-	sys_message(5, fmt "\n", ##__VA_ARGS__)
+	sys_message(5, "[TRACE] " fmt "\n", ##__VA_ARGS__)
 #define TRACE_MESSAGE(...) sys_message(6, __VA_ARGS__)
 #else
 #define TRACE(...)
diff --git a/src/system.h b/src/system.h
index 2273eaa..b625453 100644
--- a/src/system.h
+++ b/src/system.h
@@ -48,13 +48,13 @@ extern void sys_message(int lv, char *format, ...);  /* show various message */
 #define NOMEMERR()        sys_error("Out of memory at %s()\n", __func__)
 
 #define SYSERROR(fmt, ...) \
-	sys_error("*ERROR*(%s): " fmt, __func__, ##__VA_ARGS__)
+	sys_error("[ERROR] %s: " fmt, __func__, ##__VA_ARGS__)
 #define WARNING(fmt, ...) \
-	sys_message(1, "*WARNING*(%s): " fmt "\n", __func__, ##__VA_ARGS__)
+	sys_message(1, "[WARNING] %s: " fmt "\n", __func__, ##__VA_ARGS__)
 #define NOTICE(fmt, ...) \
-	sys_message(2, fmt "\n", ##__VA_ARGS__)
+	sys_message(2, "[INFO] " fmt "\n", ##__VA_ARGS__)
 #define SACT_DEBUG(fmt, ...) \
-	sys_message(5, "%s: " fmt "\n", __func__, ##__VA_ARGS__)
+	sys_message(5, "[SACT] %s: " fmt "\n", __func__, ##__VA_ARGS__)
 
 #ifdef HAVE_SIGACTION
 void sys_set_signalhandler(int SIG, void (*handler)(int));