diff --git a/src/corelib/thread/qreadwritelock_p.h b/src/corelib/thread/qreadwritelock_p.h
index 285f017655..24d25eb2be 100644
--- a/src/corelib/thread/qreadwritelock_p.h
+++ b/src/corelib/thread/qreadwritelock_p.h
@@ -65,7 +65,7 @@ class QReadWriteLockPrivate
 public:
     QReadWriteLockPrivate(bool isRecursive = false)
         : readerCount(0), writerCount(0), waitingReaders(0), waitingWriters(0),
-        recursive(isRecursive), id(0) {}
+        recursive(isRecursive), id(0), currentWriter(nullptr) {}
 
     QMutex mutex;
     QWaitCondition writerCond;