diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 1ab1ed1638..cf2537c812 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -96,6 +96,9 @@ var main_init_done chan bool
 //go:linkname main_main main.main
 func main_main()
 
+// mainStarted indicates that the main M has started.
+var mainStarted bool
+
 // runtimeInitTime is the nanotime() at which the runtime started.
 var runtimeInitTime int64
 
@@ -119,8 +122,8 @@ func main() {
 		maxstacksize = 250000000
 	}
 
-	// Record when the world started.
-	runtimeInitTime = nanotime()
+	// Allow newproc to start new Ms.
+	mainStarted = true
 
 	systemstack(func() {
 		newm(sysmon, nil)
@@ -148,6 +151,10 @@ func main() {
 		}
 	}()
 
+	// Record when the world started. Must be after runtime_init
+	// because nanotime on some platforms depends on startNano.
+	runtimeInitTime = nanotime()
+
 	gcenable()
 
 	main_init_done = make(chan bool)
@@ -3029,7 +3036,7 @@ func newproc1(fn *funcval, argp *uint8, narg int32, nret int32, callerpc uintptr
 	}
 	runqput(_p_, newg, true)
 
-	if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 && runtimeInitTime != 0 {
+	if atomic.Load(&sched.npidle) != 0 && atomic.Load(&sched.nmspinning) == 0 && mainStarted {
 		wakep()
 	}
 	_g_.m.locks--