2 files changed, 6 insertions, 2 deletions
diff --git a/src/corelib/serialization/qjsonparseerror.h b/src/corelib/serialization/qjsonparseerror.h
index 803b04c53b6..d8fc94448e6 100644
--- a/src/corelib/serialization/qjsonparseerror.h
+++ b/src/corelib/serialization/qjsonparseerror.h
@@ -7,6 +7,7 @@
 
 #include <QtCore/qtconfigmacros.h>
 #include <QtCore/qtcoreexports.h>
+#include <QtCore/qtypes.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -34,7 +35,8 @@ struct Q_CORE_EXPORT QJsonParseError
 
     QString errorString() const;
 
-    int offset = -1;
+    std::conditional_t<QT_VERSION_MAJOR < 7, int, qint64>
+    offset = -1;
     ParseError error = NoError;
 };
 
diff --git a/src/corelib/serialization/qjsonparser.cpp b/src/corelib/serialization/qjsonparser.cpp
index df266a76c79..779287adb1d 100644
--- a/src/corelib/serialization/qjsonparser.cpp
+++ b/src/corelib/serialization/qjsonparser.cpp
@@ -321,7 +321,9 @@ QCborValue Parser::parse(QJsonParseError *error)
 error:
     container.reset();
     if (error) {
-        error->offset = json - head;
+        using OffType = decltype(error->offset);
+        error->offset = OffType(json - head);
+        Q_ASSERT(error->offset == json - head);
         error->error  = lastError;
     }
     return QCborValue();