diff --git a/include/sora/hwenc_nvcodec/nvcodec_video_decoder.h b/include/sora/hwenc_nvcodec/nvcodec_video_decoder.h
index ceed5f93..c1efbde9 100644
--- a/include/sora/hwenc_nvcodec/nvcodec_video_decoder.h
+++ b/include/sora/hwenc_nvcodec/nvcodec_video_decoder.h
@@ -1,6 +1,8 @@
 #ifndef SORA_HWENC_NVCODEC_NVCODEC_VIDEO_DECODER_H_
 #define SORA_HWENC_NVCODEC_NVCODEC_VIDEO_DECODER_H_
 
+#include <optional>
+
 // WebRTC
 #include <api/video_codecs/video_decoder.h>
 #include <common_video/include/video_frame_buffer_pool.h>
diff --git a/include/sora/hwenc_vpl/vpl_video_decoder.h b/include/sora/hwenc_vpl/vpl_video_decoder.h
index 2ab8157a..3d34e87b 100644
--- a/include/sora/hwenc_vpl/vpl_video_decoder.h
+++ b/include/sora/hwenc_vpl/vpl_video_decoder.h
@@ -2,6 +2,7 @@
 #define SORA_HWENC_VPL_VPL_VIDEO_DECODER_H_
 
 #include <memory>
+#include <optional>
 
 // WebRTC
 #include <api/video/video_codec_type.h>
diff --git a/src/hwenc_nvcodec/nvcodec_video_decoder.cpp b/src/hwenc_nvcodec/nvcodec_video_decoder.cpp
index cd15b418..16f85ec6 100644
--- a/src/hwenc_nvcodec/nvcodec_video_decoder.cpp
+++ b/src/hwenc_nvcodec/nvcodec_video_decoder.cpp
@@ -113,8 +113,8 @@ int32_t NvCodecVideoDecoder::Decode(const webrtc::EncodedImage& input_image,
                                            .set_video_frame_buffer(i420_buffer)
                                            .set_timestamp_rtp(pts)
                                            .build();
-    decode_complete_callback_->Decoded(decoded_image, absl::nullopt,
-                                       absl::nullopt);
+    decode_complete_callback_->Decoded(decoded_image, std::nullopt,
+                                       std::nullopt);
 
     decoder_->UnlockFrame(frame);
   }
diff --git a/src/hwenc_vpl/vpl_video_decoder.cpp b/src/hwenc_vpl/vpl_video_decoder.cpp
index 5b837ba4..606f6ccc 100644
--- a/src/hwenc_vpl/vpl_video_decoder.cpp
+++ b/src/hwenc_vpl/vpl_video_decoder.cpp
@@ -310,8 +310,8 @@ int32_t VplVideoDecoderImpl::Decode(const webrtc::EncodedImage& input_image,
                                            .set_video_frame_buffer(i420_buffer)
                                            .set_timestamp_rtp(pts)
                                            .build();
-    decode_complete_callback_->Decoded(decoded_image, absl::nullopt,
-                                       absl::nullopt);
+    decode_complete_callback_->Decoded(decoded_image, std::nullopt,
+                                       std::nullopt);
   }
 
   return WEBRTC_VIDEO_CODEC_OK;