diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index 1bc676a36c3..4f92a81cf12 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -255,7 +255,7 @@ static void customConstruct(QVariant::Private *d, const void *copy)
         return;
     }
 
-    if (QVariant::Private::canUseInternalSpace(size)) {
+    if (QVariant::Private::canUseInternalSpace(size, type.alignOf())) {
         type.construct(&d->data, copy);
         d->is_shared = false;
     } else {
diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index 997b7ddd4a3..b2b72523a99 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -426,10 +426,11 @@ class Q_CORE_EXPORT QVariant
     {
         static constexpr size_t MaxInternalSize = 3*sizeof(void *);
         template<typename T>
-        static constexpr bool CanUseInternalSpace = (sizeof(T) <= MaxInternalSize);
-        static constexpr bool canUseInternalSpace(size_t s) { return s <= MaxInternalSize; }
+        static constexpr bool CanUseInternalSpace = (sizeof(T) <= MaxInternalSize && alignof(T) <= alignof(void *));
+        static constexpr bool canUseInternalSpace(size_t s, size_t align)
+        { return s <= MaxInternalSize && align <= alignof(void *); }
 
-        alignas(std::max_align_t) union
+        union
         {
             uchar data[MaxInternalSize] = {};
             PrivateShared *shared;