diff --git a/media/gpu/vaapi/av1_vaapi_video_encoder_delegate.cc b/media/gpu/vaapi/av1_vaapi_video_encoder_delegate.cc
index 71cad35d3cf88..4450399f574f0 100644
--- a/media/gpu/vaapi/av1_vaapi_video_encoder_delegate.cc
+++ b/media/gpu/vaapi/av1_vaapi_video_encoder_delegate.cc
@@ -648,6 +648,13 @@ AV1VaapiVideoEncoderDelegate::PrepareEncodeJob(EncodeJob& encode_job) {
       .spatial_layer_id = 0,
       .temporal_layer_id = temporal_idx.value_or(0),
   };
+  // |rate_ctrl_| was created with |num_temporal_layers_| layers. Passing a
+  // larger temporal_layer_id causes an OOB write in libaom's
+  // AV1RateControlRTC::ComputeQP / av1_save_layer_context. |svc_layers_| can
+  // be recreated with a larger T via UpdateRates() without |num_temporal_layers_|
+  // (and therefore |rate_ctrl_|'s allocation) being updated.
+  CHECK_LT(frame_params.temporal_layer_id,
+           static_cast<int>(num_temporal_layers_));
   if (rate_ctrl_->ComputeQP(frame_params) == aom::kFrameDropDecisionDrop) {
     CHECK(!encode_job.IsKeyframeRequested());
     DVLOGF(3) << "Drop frame";