diff --git a/sys/amd64/isa/clock.c b/sys/amd64/isa/clock.c
index 2809828150b..32752672b7f 100644
--- a/sys/amd64/isa/clock.c
+++ b/sys/amd64/isa/clock.c
@@ -286,6 +286,7 @@ DELAY(int n)
 		start = rdtsc();
 		end = start + (tsc_freq * n) / 1000000;
 		do {
+			cpu_spinwait();
 			now = rdtsc();
 		} while (now < end || (now > start && end < start));
 		sched_unpin();
diff --git a/sys/i386/isa/clock.c b/sys/i386/isa/clock.c
index a67db3173a5..f31c7ea2eea 100644
--- a/sys/i386/isa/clock.c
+++ b/sys/i386/isa/clock.c
@@ -291,6 +291,7 @@ DELAY(int n)
 		start = rdtsc();
 		end = start + (tsc_freq * n) / 1000000;
 		do {
+			cpu_spinwait();
 			now = rdtsc();
 		} while (now < end || (now > start && end < start));
 		sched_unpin();
diff --git a/sys/isa/atrtc.c b/sys/isa/atrtc.c
index a67db3173a5..f31c7ea2eea 100644
--- a/sys/isa/atrtc.c
+++ b/sys/isa/atrtc.c
@@ -291,6 +291,7 @@ DELAY(int n)
 		start = rdtsc();
 		end = start + (tsc_freq * n) / 1000000;
 		do {
+			cpu_spinwait();
 			now = rdtsc();
 		} while (now < end || (now > start && end < start));
 		sched_unpin();