diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -673,7 +673,7 @@
 	/*
 	 * Check for other cpus.  Return if none.
 	 */
-	if (CPU_ISFULLSET(&mask)) {
+	if (!CPU_CMP(&mask, &all_cpus)) {
 		if (mp_ncpus <= 1)
 			goto local_cb;
 	} else {
@@ -719,7 +719,7 @@
 	 * (zeroing slot) and reading from it below (wait for
 	 * acknowledgment).
 	 */
-	if (CPU_ISFULLSET(&mask)) {
+	if (!CPU_CMP(&mask, &all_cpus)) {
 		ipi_all_but_self(IPI_INVLOP);
 		other_cpus = all_cpus;
 		CPU_CLR(PCPU_GET(cpuid), &other_cpus);