diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 49daa3cc2a45..506e6037e163 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -2013,7 +2013,7 @@ int traceprobe_update_arg(struct probe_arg *arg)
 }
 
 /* When len=0, we just calculate the needed length */
-#define LEN_OR_ZERO (len ? len - pos : 0)
+#define LEN_OR_ZERO (len > pos ? len - pos : 0)
 static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
 			   enum probe_print_type ptype)
 {