diff --git a/reallog.go b/reallog.go
index 3629639..d2b91e3 100644
--- a/reallog.go
+++ b/reallog.go
@@ -32,7 +32,8 @@ func realPrintln(a ...any) {
 		reallog.Println(a...)
 	}
 	if httpMode != nil {
-		fmt.Fprintln(httpMode, fmt.Sprint(a...))
+		s := "sf:" + fmt.Sprint(a...)
+		fmt.Fprintln(httpMode, s)
 	}
 }