diff --git a/third_party/blink/renderer/platform/peerconnection/rtc_video_decoder_adapter.cc b/third_party/blink/renderer/platform/peerconnection/rtc_video_decoder_adapter.cc
index 2a387ac76f4b7..e3a3b5c8210f4 100644
--- a/third_party/blink/renderer/platform/peerconnection/rtc_video_decoder_adapter.cc
+++ b/third_party/blink/renderer/platform/peerconnection/rtc_video_decoder_adapter.cc
@@ -295,15 +295,23 @@ void RTCVideoDecoderAdapter::Impl::Initialize(
       config, /*low_delay=*/true,
       /*cdm_context=*/nullptr,
       base::BindOnce(
-          [](base::OnceCallback<void(bool)> cb,
+          [](base::WeakPtr<Impl> weak_impl, base::OnceCallback<void(bool)> cb,
              media::VideoDecoderType* decoder_type,
-             media::VideoDecoder* video_decoder, media::DecoderStatus status) {
-            *decoder_type = video_decoder->GetDecoderType();
+             media::DecoderStatus status) {
+            // The decoder may post this callback to the media task runner
+            // (e.g. MojoVideoDecoder::FailInit), where it can outlive Impl if
+            // InitializeSync() timed out and Release() destroyed Impl first.
+            // While Impl is alive the owning adapter is also alive (Release()
+            // blocks on Impl destruction), so |decoder_type| / |cb| are safe.
+            if (!weak_impl) {
+              return;
+            }
+            *decoder_type = weak_impl->video_decoder_->GetDecoderType();
             std::move(cb).Run(status.is_ok());
           },
+          weak_decoder_this_,
           ConvertToBaseOnceCallback(std::move(init_cb)),
-          CrossThreadUnretained(decoder_type),
-          CrossThreadUnretained(video_decoder_.get())),
+          CrossThreadUnretained(decoder_type)),
       output_cb, base::DoNothing());
 }