diff --git a/include/proto/trace.h b/include/proto/trace.h
index 7207233..5df7107 100644
--- a/include/proto/trace.h
+++ b/include/proto/trace.h
@@ -36,29 +36,36 @@
 #define _TRC_LOC(f,l) __TRC_LOC(f, ":", l)
 #define __TRC_LOC(f,c,l) f c #l
 
+/* truncate a macro arg list to exactly 5 args and replace missing ones with NULL */
+#define TRC_5ARGS(a1,a2,a3,a4,a5,...) DEFNULL(a1),DEFNULL(a2),DEFNULL(a3),DEFNULL(a4),DEFNULL(a5)
+
 /* For convenience, TRACE() alone uses the file's default TRACE_LEVEL, most
- * likely TRACE_LEVEL_DEVELOPER. The 4 arguments are the 4 source-specific
- * arguments that are passed to the cb() callback dedicated to decoding, and
- * which may be used for special tracking. These 4 arguments as well as the
- * cb() function pointer may all be NULL, or simply omitted (in which case
- * they will be replaced by a NULL). This ordering allows many TRACE() calls
- * to be placed using copy-paste and just change the message at the end.
+ * likely TRACE_LEVEL_DEVELOPER, though the other explicit variants specify
+ * the desired level and will work when TRACE_LEVEL is not set. The 5 optional
+ * arguments are the 4 source-specific arguments that are passed to the cb()
+ * callback dedicated to decoding, and which may be used for special tracking.
+ * These 4 arguments as well as the cb() function pointer may all be NULL, or
+ * simply omitted (in which case they will be replaced by a NULL). This
+ * ordering allows many TRACE() calls to be placed using copy-paste and just
+ * change the message at the beginning.
  */
+#define TRACE(msg, mask, ...)    \
+	trace(TRACE_LEVEL,           (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_USER(msg, mask, ...)			\
+	trace(TRACE_LEVEL_USER,      (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
-#define TRACE(mask, a1, a2, a3, a4, cb, msg)    \
-	trace(TRACE_LEVEL, (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
+#define TRACE_PAYLOAD(msg, mask, ...)  \
+	trace(TRACE_LEVEL_PAYLOAD,   (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_PROTO(msg, mask, ...)    \
+	trace(TRACE_LEVEL_PROTO,     (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+
+#define TRACE_STATE(msg, mask, ...)    \
+	trace(TRACE_LEVEL_STATE,     (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
-/* and explicit trace levels (recommended) */
-#define TRACE_USER(mask, a1, a2, a3, a4, cb, msg)     \
-	trace(TRACE_LEVEL_USER,      (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_PAYLOAD(mask, a1, a2, a3, a4, cb, msg)  \
-	trace(TRACE_LEVEL_PAYLOAD,   (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_PROTO(mask, a1, a2, a3, a4, cb, msg)    \
-	trace(TRACE_LEVEL_PROTO,     (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_STATE(mask, a1, a2, a3, a4, cb, msg)    \
-	trace(TRACE_LEVEL_STATE,     (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
-#define TRACE_DEVEL(mask, a1, a2, a3, a4, cb, msg)    \
-	trace(TRACE_LEVEL_DEVELOPER, (mask), TRACE_SOURCE, ist(TRC_LOC), DEFNULL(a1), DEFNULL(a2), DEFNULL(a3), DEFNULL(a4), DEFNULL(cb), ist(msg))
+#define TRACE_DEVEL(msg, mask, ...)    \
+	trace(TRACE_LEVEL_DEVELOPER, (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
 extern struct list trace_sources;
 extern THREAD_LOCAL struct buffer trace_buf;