diff --git a/share/qtcreator/qml/qmlpuppet/commands/valueschangedcommand.cpp b/share/qtcreator/qml/qmlpuppet/commands/valueschangedcommand.cpp
index 636074074e6..cb7a3164263 100644
--- a/share/qtcreator/qml/qmlpuppet/commands/valueschangedcommand.cpp
+++ b/share/qtcreator/qml/qmlpuppet/commands/valueschangedcommand.cpp
@@ -112,7 +112,9 @@ QDataStream &operator<<(QDataStream &out, const ValuesChangedCommand &command)
         QSharedMemory *sharedMemory = createSharedMemory(keyCounter, outDataStreamByteArray.size());
 
         if (sharedMemory) {
+            sharedMemory->lock();
             std::memcpy(sharedMemory->data(), outDataStreamByteArray.constData(), sharedMemory->size());
+            sharedMemory->unlock();
             out << command.keyNumber();
             return out;
         }