diff --git a/slides/cours_10.md b/slides/cours_10.md
index dd1ea96ae955826da88100f11490fc0195ebb4bc..d92528677e703cbbcf711c4fbc3b0f459879ce61 100644
--- a/slides/cours_10.md
+++ b/slides/cours_10.md
@@ -320,7 +320,7 @@ Caractère lu        Pile opérandes
 . . .
 
 ```C
-bool evaluate(char *postfix, double *val) { // init stack
+double evaluate(char *postfix, double *val) { // init stack
     for (size_t i = 0; i < strlen(postfix); ++i) {
         if (is_operand(postfix[i])) {
             stack_push(&s, postfix[i]);