diff --git a/libavcodec/g729dec.c b/libavcodec/g729dec.c
index 32218e5989..908c12a73a 100644
--- a/libavcodec/g729dec.c
+++ b/libavcodec/g729dec.c
@@ -416,7 +416,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr,
         return ret;
     out_frame = (int16_t*) frame->data[0];
 
-    if (buf_size % 10 == 0) {
+    if (buf_size && buf_size % 10 == 0) {
         packet_type = FORMAT_G729_8K;
         format = &format_g729_8k;
         //Reset voice decision