diff --git a/slides/cours_11.md b/slides/cours_11.md
index a59430ab56c1ac36cf9b2a9e943ac39d6d56c941..7e37204e4cabb0fd5be08f8ba6b7070ee73c7ad1 100644
--- a/slides/cours_11.md
+++ b/slides/cours_11.md
@@ -88,7 +88,7 @@ Caractère lu        Pile opérandes
 . . .
 
 ```C
-bool evaluate(char *postfix, double *val) { // init stack
+double evaluate(char *postfix) { // init stack
     for (size_t i = 0; i < strlen(postfix); ++i) {
         if (is_operand(postfix[i])) {
             stack_push(&s, postfix[i]);