diff --git a/stack.c b/stack.c
index 0c1c9eef7d337bf50b479bca1c6181ca115ba417..209089f62fb348a0d4779d667f6aba8bc2a0c1a1 100644
--- a/stack.c
+++ b/stack.c
@@ -1,5 +1,7 @@
 #include <stdlib.h>
 #include <stdbool.h>
+#include <stdio.h>
+
 #include "stack.h"
 
 
diff --git a/stack.h b/stack.h
index 010bfdc0153b05dbe62b975fe51830c6ac26f26e..5aa60b4888579fba047ae8a656f61b86846b39bf 100644
--- a/stack.h
+++ b/stack.h
@@ -1,7 +1,6 @@
 #ifndef _STACK_H_
 #define _STACK_H_
 
-
 typedef struct _stack {
     int *data;
     int capacity;
@@ -17,6 +16,7 @@ void stack_pop(stack *s, int *value);
 void stack_peek(stack s, int *value);
 void stack_clone(stack s, stack *clone);
 int get_length(stack s);
+bool stack_is_empty(stack s);
 
 void stack_print(const stack s);