diff --git a/mediapipe/tasks/cc/genai/inference/proto/transformer_params.proto b/mediapipe/tasks/cc/genai/inference/proto/transformer_params.proto
index c87f758e82..61de8f308f 100644
--- a/mediapipe/tasks/cc/genai/inference/proto/transformer_params.proto
+++ b/mediapipe/tasks/cc/genai/inference/proto/transformer_params.proto
@@ -194,6 +194,7 @@ message TransformerParameters {
 
   // Vision parameters
   int32 vision_tokens_num = 26;
+  int32 max_num_images = 28;
 
   // The number of stacks that are treated as "extra", which may have slightly
   // different loading behavior.