diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index caeb51205b..45d98de151 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -1399,6 +1399,7 @@ func needm(x byte) {
 	// running at all (that is, there's no garbage collection
 	// running right now).
 	mp.needextram = mp.schedlink == 0
+	extraMCount--
 	unlockextra(mp.schedlink.ptr())
 
 	// Save and block signals before installing g.
@@ -1484,6 +1485,7 @@ func oneNewExtraM() {
 	// Add m to the extra list.
 	mnext := lockextra(true)
 	mp.schedlink.set(mnext)
+	extraMCount++
 	unlockextra(mp)
 }
 
@@ -1525,6 +1527,7 @@ func dropm() {
 	unminit()
 
 	mnext := lockextra(true)
+	extraMCount++
 	mp.schedlink.set(mnext)
 
 	setg(nil)
@@ -1541,6 +1544,7 @@ func getm() uintptr {
 }
 
 var extram uintptr
+var extraMCount uint32 // Protected by lockextra
 var extraMWaiters uint32
 
 // lockextra locks the extra list and returns the list head.
diff --git a/src/runtime/signal_sighandler.go b/src/runtime/signal_sighandler.go
index 5af12d7b2f..3b9ba296d9 100644
--- a/src/runtime/signal_sighandler.go
+++ b/src/runtime/signal_sighandler.go
@@ -111,7 +111,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 
 	if docrash {
 		crashing++
-		if crashing < sched.mcount {
+		if crashing < sched.mcount-int32(extraMCount) {
 			// There are other m's that need to dump their stacks.
 			// Relay SIGQUIT to the next m by sending it to the current process.
 			// All m's that have already received SIGQUIT have signal masks blocking