diff --git a/cast.hpp b/cast.hpp
index 3ecd03ae..07177a0f 100644
--- a/cast.hpp
+++ b/cast.hpp
@@ -223,7 +223,7 @@ namespace cruft::cast {
     /// CXX#20: Convert instances of me to std::bit_cast when it becomes
     /// available in supported compilers.
     template <typename DstT, typename SrcT>
-    DstT
+    constexpr DstT
     bit (SrcT &&src)
     {
         static_assert (sizeof (DstT) == sizeof (SrcT));