diff --git a/clients/labnag.c b/clients/labnag.c
index 31ac4e9d..237ee958 100644
--- a/clients/labnag.c
+++ b/clients/labnag.c
@@ -1388,6 +1388,7 @@ nag_setup(struct nag *nag)
 	}
 
 	sigset_t mask;
+	sigemptyset(&mask);
 	sigaddset(&mask, SIGINT);
 	sigaddset(&mask, SIGTERM);
 	sigprocmask(SIG_BLOCK, &mask, NULL);