diff --git a/slides/cours_11.md b/slides/cours_11.md
index 63be99a02861c4f63cffedc3ed2dbb79dfd92213..73689f4f965377fcaab202ef70c14203100ef8e7 100644
--- a/slides/cours_11.md
+++ b/slides/cours_11.md
@@ -216,7 +216,7 @@ void stack_peek(stack s, int *val) {
 . . .
 
 ```C
-void stack_pop(stack *s, int *val) {
+int stack_pop(stack *s, int *val) {
     stack_peek(*s, val);
     element *tmp = *s;
     *s = (*s)->next;