diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index 2db4e07c99..c7d9c9767a 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -560,7 +560,9 @@ static bool convert(const QVariant::Private *d, int t, void *result, bool *ok)
         if (d->type == QVariant::List) {
             QStringList *slst = static_cast<QStringList *>(result);
             const QVariantList *list = v_cast<QVariantList >(d);
-            for (int i = 0; i < list->size(); ++i)
+            const int size = list->size();
+            slst->reserve(size);
+            for (int i = 0; i < size; ++i)
                 slst->append(list->at(i).toString());
         } else if (d->type == QVariant::String) {
             QStringList *slst = static_cast<QStringList *>(result);
@@ -826,7 +828,9 @@ static bool convert(const QVariant::Private *d, int t, void *result, bool *ok)
         if (d->type == QVariant::StringList) {
             QVariantList *lst = static_cast<QVariantList *>(result);
             const QStringList *slist = v_cast<QStringList>(d);
-            for (int i = 0; i < slist->size(); ++i)
+            const int size = slist->size();
+            lst->reserve(size);
+            for (int i = 0; i < size; ++i)
                 lst->append(QVariant(slist->at(i)));
         } else if (qstrcmp(QMetaType::typeName(d->type), "QList<QVariant>") == 0) {
             *static_cast<QVariantList *>(result) =