diff --git a/src/corelib/thread/qreadwritelock.cpp b/src/corelib/thread/qreadwritelock.cpp
index c60580b9f3..c31782d684 100644
--- a/src/corelib/thread/qreadwritelock.cpp
+++ b/src/corelib/thread/qreadwritelock.cpp
@@ -422,6 +422,7 @@ QReadWriteLock::StateForWaitCondition QReadWriteLock::stateForWaitCondition() co
 
     if (!d)
         return Unlocked;
+    const auto lock = qt_scoped_lock(d->mutex);
     if (d->writerCount > 1)
         return RecursivelyLocked;
     else if (d->writerCount == 1)