diff --git a/examples/av1_dec_fuzzer.cc b/examples/av1_dec_fuzzer.cc
index d2bfee1..937c944 100644
--- a/examples/av1_dec_fuzzer.cc
+++ b/examples/av1_dec_fuzzer.cc
@@ -37,7 +37,7 @@
   const aom_codec_iface_t *codec_interface = aom_codec_av1_dx();
   aom_codec_ctx_t codec;
   // Set thread count in the range [1, 64].
-  const unsigned int threads = (data[0] & 0x3f) + 1;
+  const unsigned int threads = (data[IVF_FILE_HDR_SZ] & 0x3f) + 1;
   aom_codec_dec_cfg_t cfg = { threads, 0, 0, CONFIG_LOWBITDEPTH, { 1 } };
   if (aom_codec_dec_init(&codec, codec_interface, &cfg, 0)) {
     return 0;