diff --git a/signaux/ex3/prog.c b/signaux/ex3/prog.c
index 01202e0e405eb0bb046d89fd69bf337800d1f15c..5e4add3b772eb1c2e028715d5d304c66afe69af5 100644
--- a/signaux/ex3/prog.c
+++ b/signaux/ex3/prog.c
@@ -57,6 +57,11 @@ int main(void) {
         perror("sigaddset");
     }
 
+    if (sigprocmask(SIG_SETMASK, &usr1.sa_mask, NULL) == -1) {
+        perror("sigprocmask");
+        exit(EXIT_FAILURE);
+    }
+
     if (sigaction(SIGUSR1, &usr1, NULL) == -1) {
         perror("sigaction");
         exit(EXIT_FAILURE);