diff --git a/blink/renderer/platform/image-decoders/heif/heif_image_decoder.cc b/blink/renderer/platform/image-decoders/heif/heif_image_decoder.cc
index e383bddd72f886bc4b38610a2690e3b3ececb333..0a71c1b2a5b4cfd05b06841a7cf2afe44614b840 100644
--- a/blink/renderer/platform/image-decoders/heif/heif_image_decoder.cc
+++ b/blink/renderer/platform/image-decoders/heif/heif_image_decoder.cc
@@ -131,7 +131,7 @@ bool CheckFormat(const void* header_data, uint32_t data_size) {
   }
 
   uint32_t tmp_buff[kHeaderSize];
-  if (memcpy_s(tmp_buff, kHeaderSize, header_data, kHeaderSize) != EOK) {
+  if (memcpy_s(tmp_buff, kHeaderSize, header_data, data_size) != EOK) {
     return false;
   }