diff --git a/sdk/android/src/jni/video_encoder_wrapper.cc b/sdk/android/src/jni/video_encoder_wrapper.cc
index c12f5cff52..dde82a53a9 100644
--- a/sdk/android/src/jni/video_encoder_wrapper.cc
+++ b/sdk/android/src/jni/video_encoder_wrapper.cc
@@ -113,7 +113,10 @@ int32_t VideoEncoderWrapper::Release() {
   int32_t status = JavaToNativeVideoCodecStatus(
       jni, Java_VideoEncoder_release(jni, encoder_));
   RTC_LOG(LS_INFO) << "release: " << status;
-  frame_extra_infos_.clear();
+  {
+    MutexLock lock(&frame_extra_infos_lock_);
+    frame_extra_infos_.clear();
+  }
   initialized_ = false;
 
   return status;
@@ -138,7 +141,10 @@ int32_t VideoEncoderWrapper::Encode(
   FrameExtraInfo info;
   info.capture_time_ns = frame.timestamp_us() * rtc::kNumNanosecsPerMicrosec;
   info.timestamp_rtp = frame.timestamp();
-  frame_extra_infos_.push_back(info);
+  {
+    MutexLock lock(&frame_extra_infos_lock_);
+    frame_extra_infos_.push_back(info);
+  }
 
   ScopedJavaLocalRef<jobject> j_frame = NativeToJavaVideoFrame(jni, frame);
   ScopedJavaLocalRef<jobject> ret =
@@ -229,19 +235,23 @@ void VideoEncoderWrapper::OnEncodedFrame(
   // entries that don't belong to us, and we need to be careful not to
   // remove them. Removing only those entries older than the current frame
   // provides this guarantee.
-  while (!frame_extra_infos_.empty() &&
-         frame_extra_infos_.front().capture_time_ns < capture_time_ns) {
+  FrameExtraInfo frame_extra_info;
+  {
+    MutexLock lock(&frame_extra_infos_lock_);
+    while (!frame_extra_infos_.empty() &&
+           frame_extra_infos_.front().capture_time_ns < capture_time_ns) {
+      frame_extra_infos_.pop_front();
+    }
+    if (frame_extra_infos_.empty() ||
+        frame_extra_infos_.front().capture_time_ns != capture_time_ns) {
+      RTC_LOG(LS_WARNING)
+          << "Java encoder produced an unexpected frame with timestamp: "
+          << capture_time_ns;
+      return;
+    }
+    frame_extra_info = frame_extra_infos_.front();
     frame_extra_infos_.pop_front();
   }
-  if (frame_extra_infos_.empty() ||
-      frame_extra_infos_.front().capture_time_ns != capture_time_ns) {
-    RTC_LOG(LS_WARNING)
-        << "Java encoder produced an unexpected frame with timestamp: "
-        << capture_time_ns;
-    return;
-  }
-  FrameExtraInfo frame_extra_info = std::move(frame_extra_infos_.front());
-  frame_extra_infos_.pop_front();
 
   // This is a bit subtle. The |frame| variable from the lambda capture is
   // const. Which implies that (i) we need to make a copy to be able to
diff --git a/sdk/android/src/jni/video_encoder_wrapper.h b/sdk/android/src/jni/video_encoder_wrapper.h
index cee3a609a3..bb098bb7c7 100644
--- a/sdk/android/src/jni/video_encoder_wrapper.h
+++ b/sdk/android/src/jni/video_encoder_wrapper.h
@@ -21,6 +21,7 @@
 #include "api/video_codecs/video_encoder.h"
 #include "common_video/h264/h264_bitstream_parser.h"
 #include "modules/video_coding/codecs/vp9/include/vp9_globals.h"
+#include "rtc_base/synchronization/mutex.h"
 #include "sdk/android/src/jni/jni_helpers.h"
 #include "sdk/android/src/jni/video_frame.h"
 
@@ -82,7 +83,10 @@ class VideoEncoderWrapper : public VideoEncoder {
   const ScopedJavaGlobalRef<jobject> encoder_;
   const ScopedJavaGlobalRef<jclass> int_array_class_;
 
-  std::deque<FrameExtraInfo> frame_extra_infos_;
+  // Modified both on the encoder thread and the callback thread.
+  Mutex frame_extra_infos_lock_;
+  std::deque<FrameExtraInfo> frame_extra_infos_
+      RTC_GUARDED_BY(frame_extra_infos_lock_);
   EncodedImageCallback* callback_;
   bool initialized_;
   int num_resets_;