diff --git a/tools/kwbimage.c b/tools/kwbimage.c
index 3ca3b3b..26686ad 100644
--- a/tools/kwbimage.c
+++ b/tools/kwbimage.c
@@ -1616,6 +1616,10 @@ static int kwbimage_verify_header(unsigned char *ptr, int image_size,
 				  struct image_tool_params *params)
 {
 	uint8_t checksum;
+	size_t header_size = kwbimage_header_size(ptr);
+
+	if (header_size > image_size)
+		return -FDT_ERR_BADSTRUCTURE;
 
 	if (!main_hdr_checksum_ok(ptr))
 		return -FDT_ERR_BADSTRUCTURE;