diff --git a/include/boost/variant2/variant.hpp b/include/boost/variant2/variant.hpp
index 311d83b..ed36b26 100644
--- a/include/boost/variant2/variant.hpp
+++ b/include/boost/variant2/variant.hpp
@@ -856,8 +856,16 @@ template<std::size_t N> using get_smallest_unsigned_type = mp11::mp_cond<
 
 >;
 
+#if BOOST_WORKAROUND( BOOST_CLANG_VERSION, < 30800 )
+
+template<bool Double, class... T> using get_index_type = unsigned short;
+
+#else
+
 template<bool Double, class... T> using get_index_type = get_smallest_unsigned_type< (Double + 1) * sizeof...(T) >;
 
+#endif
+
 // variant_base
 
 template<bool is_trivially_destructible, bool is_single_buffered, class... T> struct variant_base_impl;