diff --git a/libavcodec/wmaprodec.c b/libavcodec/wmaprodec.c
index e4309ad975..e04df49266 100644
--- a/libavcodec/wmaprodec.c
+++ b/libavcodec/wmaprodec.c
@@ -86,6 +86,7 @@
  * subframe in order to reconstruct the output samples.
  */
 
+#include "libavutil/avassert.h"
 #include "libavutil/intfloat.h"
 #include "libavutil/intreadwrite.h"
 #include "avcodec.h"
@@ -1177,6 +1178,7 @@ static int decode_subframe(WMAProDecodeCtx *s)
             transmit_coeffs = 1;
     }
 
+    av_assert0(s->subframe_len <= WMAPRO_BLOCK_MAX_SIZE);
     if (transmit_coeffs) {
         int step;
         int quant_step = 90 * s->bits_per_sample >> 4;
@@ -1187,10 +1189,11 @@ static int decode_subframe(WMAProDecodeCtx *s)
             for (i = 0; i < s->channels_for_cur_subframe; i++) {
                 int c = s->channel_indexes_for_cur_subframe[i];
                 int num_vec_coeffs = get_bits(&s->gb, num_bits) << 2;
-                if (num_vec_coeffs + offset > FF_ARRAY_ELEMS(s->channel[c].out)) {
+                if (num_vec_coeffs > s->subframe_len) {
                     av_log(s->avctx, AV_LOG_ERROR, "num_vec_coeffs %d is too large\n", num_vec_coeffs);
                     return AVERROR_INVALIDDATA;
                 }
+                av_assert0(num_vec_coeffs + offset <= FF_ARRAY_ELEMS(s->channel[c].out));
                 s->channel[c].num_vec_coeffs = num_vec_coeffs;
             }
         } else {