diff --git a/libavcodec/wmv2enc.c b/libavcodec/wmv2enc.c
index 6aeee59ab2a63a2061685e3084b5136861d31bcf..869b3c7fe41d766d498a019cb26b51e9382b329e 100644
--- a/libavcodec/wmv2enc.c
+++ b/libavcodec/wmv2enc.c
@@ -60,7 +60,9 @@ static av_cold int wmv2_encode_init(AVCodecContext *avctx){
     ff_wmv2_common_init(w);
 
     avctx->extradata_size= 4;
-    avctx->extradata= av_mallocz(avctx->extradata_size + 10);
+    avctx->extradata= av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!avctx->extradata)
+        return AVERROR(ENOMEM);
     encode_ext_header(w);
 
     return 0;