diff --git a/apps/shell/shell.c b/apps/shell/shell.c
index 7a18c65..92a73a7 100644
--- a/apps/shell/shell.c
+++ b/apps/shell/shell.c
@@ -485,7 +485,7 @@ com_send(struct command *com)
 {
   int i;
   err_t err;
-  int len;
+  size_t len;
   
   i = strtol(com->args[0], NULL, 10);