diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1268,6 +1268,9 @@
 	ets.tv_nsec = 0;
 	traced = false;
 
+	/* Ensure the sigfastblock value is up to date. */
+	sigfastblock_fetch(td);
+
 	if (timeout != NULL) {
 		if (timeout->tv_nsec >= 0 && timeout->tv_nsec < 1000000000) {
 			timevalid = 1;
@@ -1527,6 +1530,9 @@
 	struct proc *p = td->td_proc;
 	int has_sig, sig;
 
+	/* Ensure the sigfastblock value is up to date. */
+	sigfastblock_fetch(td);
+
 	/*
 	 * When returning from sigsuspend, we want
 	 * the old mask to be restored after the