1 files changed, 3 insertions, 0 deletions
diff --git a/src/corelib/global/qflags.h b/src/corelib/global/qflags.h
index 7cf06d7e88..faacf7321c 100644
--- a/src/corelib/global/qflags.h
+++ b/src/corelib/global/qflags.h
@@ -77,6 +77,9 @@ Q_DECL_CONSTEXPR inline QIncompatibleFlag::QIncompatibleFlag(int ai) : i(ai) {}
 template<typename Enum>
 class QFlags
 {
+    Q_STATIC_ASSERT_X((sizeof(Enum) <= sizeof(int)),
+                      "QFlags uses an int as storage, so an enum with underlying "
+                      "long long would overflow. Qt 5.1 will have support for 64bit enums.");
     struct Private;
     typedef int (Private::*Zero);
     int i;