diff --git a/src/runtime/lock_spinbit.go b/src/runtime/lock_spinbit.go
index ba5268abdd..7b7bc651ad 100644
--- a/src/runtime/lock_spinbit.go
+++ b/src/runtime/lock_spinbit.go
@@ -143,7 +143,7 @@ func mutexPreferLowLatency(l *mutex) bool {
 }
 
 func mutexContended(l *mutex) bool {
-	return atomic.Loaduintptr(&l.key) > mutexLocked
+	return atomic.Loaduintptr(&l.key)&^mutexMMask != 0
 }
 
 func lock(l *mutex) {