diff --git a/src/runtime/mgcscavenge.go b/src/runtime/mgcscavenge.go
index 286aa1bbaef..0399c2d21c2 100644
--- a/src/runtime/mgcscavenge.go
+++ b/src/runtime/mgcscavenge.go
@@ -344,6 +344,11 @@ func bgscavenge(c chan int) {
 				crit += float64(end - start)
 			}
 			released += r
+
+			// When using fake time just do one loop.
+			if faketime != 0 {
+				break
+			}
 		}
 
 		if released == 0 {
diff --git a/src/runtime/time_fake.go b/src/runtime/time_fake.go
index 107f6be335a..b5e04635883 100644
--- a/src/runtime/time_fake.go
+++ b/src/runtime/time_fake.go
@@ -41,6 +41,10 @@ func time_now() (sec int64, nsec int32, mono int64) {
 	return faketime / 1e9, int32(faketime % 1e9), faketime
 }
 
+// write is like the Unix write system call.
+// We have to avoid write barriers to avoid potential deadlock
+// on write calls.
+//go:nowritebarrierrec
 func write(fd uintptr, p unsafe.Pointer, n int32) int32 {
 	if !(fd == 1 || fd == 2) {
 		// Do an ordinary write.