diff --git a/manual/examples/sigusr.c b/manual/examples/sigusr.c
index 13874fd7d8..8f00cd9407 100644
--- a/manual/examples/sigusr.c
+++ b/manual/examples/sigusr.c
@@ -18,6 +18,7 @@
 /*@group*/
 #include <signal.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 /*@end group*/