diff --git a/vtysh/vtysh_main.c b/vtysh/vtysh_main.c
index 48958f0..893c1a1 100644
--- a/vtysh/vtysh_main.c
+++ b/vtysh/vtysh_main.c
@@ -202,9 +202,12 @@
 {
   time_t t = time(NULL);
   struct tm *tmp = localtime(&t);
-  char *user = getenv("USER") ? : "boot";
+  const char *user = getenv("USER");
   char tod[64];
 
+  if (!user)
+    user = "boot";
+
   strftime(tod, sizeof tod, "%Y%m%d-%H:%M.%S", tmp);
   
   fprintf(logfile, "%s:%s %s\n", tod, user, line);