diff --git a/modules/video_coding/svc/simulcast_to_svc_converter.cc b/modules/video_coding/svc/simulcast_to_svc_converter.cc
index f7575e7fbc..77d5b294b5 100644
--- a/modules/video_coding/svc/simulcast_to_svc_converter.cc
+++ b/modules/video_coding/svc/simulcast_to_svc_converter.cc
@@ -84,15 +84,17 @@ bool SimulcastToSvcConverter::ConvertFrame(EncodedImage& encoded_image,
   encoded_image.SetSimulcastIndex(sid);
   encoded_image.SetSpatialIndex(std::nullopt);
   codec_specific.end_of_picture = true;
-  int num_temporal_layers =
-      ScalabilityModeToNumTemporalLayers(*codec_specific.scalability_mode);
-  RTC_DCHECK_LE(num_temporal_layers, 3);
-  if (num_temporal_layers == 1) {
-    codec_specific.scalability_mode = ScalabilityMode::kL1T1;
-  } else if (num_temporal_layers == 2) {
-    codec_specific.scalability_mode = ScalabilityMode::kL1T2;
-  } else if (num_temporal_layers == 3) {
-    codec_specific.scalability_mode = ScalabilityMode::kL1T3;
+  if (codec_specific.scalability_mode) {
+    int num_temporal_layers =
+        ScalabilityModeToNumTemporalLayers(*codec_specific.scalability_mode);
+    RTC_DCHECK_LE(num_temporal_layers, 3);
+    if (num_temporal_layers == 1) {
+      codec_specific.scalability_mode = ScalabilityMode::kL1T1;
+    } else if (num_temporal_layers == 2) {
+      codec_specific.scalability_mode = ScalabilityMode::kL1T2;
+    } else if (num_temporal_layers == 3) {
+      codec_specific.scalability_mode = ScalabilityMode::kL1T3;
+    }
   }
   CodecSpecificInfoVP9& vp9_info = codec_specific.codecSpecific.VP9;
   vp9_info.num_spatial_layers = 1;