diff --git a/src/testlib/qsignalspy.h b/src/testlib/qsignalspy.h
index 117d4858994..a60ae05e18e 100644
--- a/src/testlib/qsignalspy.h
+++ b/src/testlib/qsignalspy.h
@@ -193,7 +193,7 @@ private:
         QMutexLocker locker(&m_mutex);
         QList<QVariant> list;
         list.reserve(args.size());
-        for (int i = 0; i < args.size(); ++i) {
+        for (qsizetype i = 0; i < args.size(); ++i) {
             const QMetaType::Type type = static_cast<QMetaType::Type>(args.at(i));
             if (type == QMetaType::QVariant)
                 list << *reinterpret_cast<QVariant *>(a[i + 1]);