diff --git a/libavcodec/vmnc.c b/libavcodec/vmnc.c
index 62a1312de6..d3c86f1f97 100644
--- a/libavcodec/vmnc.c
+++ b/libavcodec/vmnc.c
@@ -332,6 +332,10 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPac
     src += 2;
     chunks = AV_RB16(src); src += 2;
     while(chunks--) {
+        if(buf_size - (src - buf) < 12) {
+            av_log(avctx, AV_LOG_ERROR, "Premature end of data!\n");
+            return -1;
+        }
         dx = AV_RB16(src); src += 2;
         dy = AV_RB16(src); src += 2;
         w  = AV_RB16(src); src += 2;