diff --git a/libavcodec/rv34.c b/libavcodec/rv34.c
index 914bde4a2a..ed630cd597 100644
--- a/libavcodec/rv34.c
+++ b/libavcodec/rv34.c
@@ -97,6 +97,8 @@ static av_cold void rv34_gen_vlc_ext(const uint8_t *bits, int size, VLC *vlc,
     uint16_t cw[MAX_VLC_SIZE];
     int maxbits;
 
+    av_assert1(size > 0);
+
     for (int i = 0; i < size; i++)
         counts[bits[i]]++;