diff --git a/upb/collections/message_value.h b/upb/collections/message_value.h
index 7287db1b20..c0d2edad31 100644
--- a/upb/collections/message_value.h
+++ b/upb/collections/message_value.h
@@ -25,6 +25,9 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+// Users should include array.h or map.h instead.
+// IWYU pragma: private, include "third_party/upb/upb/collections/array.h"
+
 #ifndef UPB_MESSAGE_VALUE_H_
 #define UPB_MESSAGE_VALUE_H_