diff --git a/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp b/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp
index 5c1b6c97b1..aec1e91360 100644
--- a/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp
+++ b/dom/media/platforms/ffmpeg/FFmpegVideoDecoder.cpp
@@ -181,8 +181,8 @@ FFmpegVideoDecoder<LIBAV_VER>::DoDecode(MediaRawData* aSample, bool* aGotFrame)
 #endif
       )) {
     while (inputSize) {
-      uint8_t* data;
-      int size;
+      uint8_t* data = inputData;
+      int size = inputSize;
       int len = mLib->av_parser_parse2(mCodecParser, mCodecContext, &data, &size,
                                        inputData, inputSize,
                                        aSample->mTime, aSample->mTimecode,