diff --git a/src/corelib/json/qjsonparser.cpp b/src/corelib/json/qjsonparser.cpp
index 0d62687388..b8a628fdcc 100644
--- a/src/corelib/json/qjsonparser.cpp
+++ b/src/corelib/json/qjsonparser.cpp
@@ -732,7 +732,7 @@ bool Parser::parseNumber(QJsonPrivate::Value *val, int baseOffset)
     }
 
     int pos = reserveSpace(sizeof(double));
-    *(quint64 *)(data + pos) = qToLittleEndian(ui);
+    qToLittleEndian(ui, reinterpret_cast<uchar *>(data + pos));
     if (current - baseOffset >= Value::MaxSize) {
         lastError = QJsonParseError::DocumentTooLarge;
         return false;