diff --git a/block.c b/block.c
index c24fb0a1..776071ed 100644
--- a/block.c
+++ b/block.c
@@ -234,12 +234,16 @@ static int block_child_sig(struct block *block)
 {
 	sigset_t set;
 	int err;
+	unsigned int i;
 
 	/* It'd be safe to assume that all signals are unblocked by default */
 	err = sys_sigfillset(&set);
 	if (err)
 		return err;
 
+	for (i = 0; i <= SIGRTMAX - SIGRTMIN; i++)
+		sys_sigdelset(&set, SIGRTMIN + i);
+
 	return sys_sigunblock(&set);
 }
 
diff --git a/sys.c b/sys.c
index b7f770de..a07c9573 100644
--- a/sys.c
+++ b/sys.c
@@ -203,6 +203,20 @@ int sys_sigaddset(sigset_t *set, int sig)
 	return 0;
 }
 
+int sys_sigdelset(sigset_t *set, int sig)
+{
+	int rc;
+
+	rc = sigdelset(set, sig);
+	if (rc == -1) {
+		sys_errno("sigdelset(%d (%s))", sig, strsignal(sig));
+		rc = -errno;
+		return rc;
+	}
+
+	return 0;
+}
+
 static int sys_sigprocmask(const sigset_t *set, int how)
 {
 	int rc;
diff --git a/sys.h b/sys.h
index 98feaac8..f8b5517a 100644
--- a/sys.h
+++ b/sys.h
@@ -38,6 +38,7 @@ const char *sys_getenv(const char *name);
 int sys_sigemptyset(sigset_t *set);
 int sys_sigfillset(sigset_t *set);
 int sys_sigaddset(sigset_t *set, int sig);
+int sys_sigdelset(sigset_t *set, int sig);
 int sys_sigunblock(const sigset_t *set);
 int sys_sigsetmask(const sigset_t *set);
 int sys_sigwaitinfo(sigset_t *set, int *sig, int *fd);