diff --git a/src/google/protobuf/port_def.inc b/src/google/protobuf/port_def.inc
index a512b4843..31f1f5a12 100644
--- a/src/google/protobuf/port_def.inc
+++ b/src/google/protobuf/port_def.inc
@@ -678,6 +678,9 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #  define PROTOBUF_CONSTINIT
 #  define PROTOBUF_CONSTEXPR constexpr
 # endif
+#elif defined(_MSC_VER)  && defined(__clang__)
+#  define PROTOBUF_CONSTINIT
+#  define PROTOBUF_CONSTEXPR constexpr
 #else
 # if defined(__cpp_constinit) && !defined(__CYGWIN__)
 #  define PROTOBUF_CONSTINIT constinit