diff --git a/_web_server/server/playground-server.scm b/_web_server/server/playground-server.scm
index 88eda9c..4dbbce0 100755
--- a/_web_server/server/playground-server.scm
+++ b/_web_server/server/playground-server.scm
@@ -78,7 +78,7 @@
 ;;; Logger
 ;;;
 (define (logger . args)
-  (when (not (null? args))
+  (unless (null? args)
     (let ((prefix
            (format "~a | "
                    (strftime "%c" (localtime (current-time))))))
@@ -179,7 +179,7 @@
             (when (or (not max-file-size)
                       (< readed max-file-size))
               (let ((data (get-bytevector-n in max-read-length)))
-                (when (not (eof-object? data))
+                (unless (eof-object? data)
                   (put-bytevector port data)
                   (loop (+ readed (bytevector-length data))))))))
         #:binary #t))))