diff --git a/tl/expected.hpp b/tl/expected.hpp
index f19e8da..b85ca57 100644
--- a/tl/expected.hpp
+++ b/tl/expected.hpp
@@ -75,20 +75,20 @@
 // for non-copyable types
 #elif (defined(__GNUC__) && __GNUC__ < 8 &&                                                \
      !defined(__clang__))
-#ifdef _GLIBCXX_VECTOR
 #ifndef TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
 #define TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
 namespace tl {
   namespace detail {
       template<class T>
       struct is_trivially_copy_constructible : std::is_trivially_copy_constructible<T>{};
+#ifdef _GLIBCXX_VECTOR
       template<class T, class A>
       struct is_trivially_copy_constructible<std::vector<T,A>>
           : std::is_trivially_copy_constructible<T>{};
+#endif
   }
 }
 #endif
-#endif
 
 #define TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T)                                     \
   tl::detail::is_trivially_copy_constructible<T>