diff --git a/demos/demo_utils.h b/demos/demo_utils.h
index 619bb1fa..bd915cdd 100644
--- a/demos/demo_utils.h
+++ b/demos/demo_utils.h
@@ -4,9 +4,9 @@
 #ifndef DEMO_UTILS_H
 #define DEMO_UTILS_H
 
-#include <stdlib.h>
+#include <stddef.h>
 
-#define MAX_INPUT_SIZE 128 /* size of all input buffers in the demo */
+#define MAX_INPUT_SIZE 4096 /* max size of all input buffers in the demo */
 
 void print_hex(const void *bin, const size_t bin_len);
 size_t prompt_input(char *prompt, char *input, const size_t max_input_len);