diff --git a/tools/rksd.c b/tools/rksd.c
index ff2233f..e55c522 100644
--- a/tools/rksd.c
+++ b/tools/rksd.c
@@ -43,8 +43,8 @@ static void rksd_set_header(void *buf,  struct stat *sbuf,  int ifd,
 	       RK_SPL_HDR_SIZE);
 
 	if (rkcommon_need_rc4_spl(params))
-		rkcommon_rc4_encode_spl(buf, RK_SPL_START - 4,
-					params->file_size - RK_SPL_START + 4);
+		rkcommon_rc4_encode_spl(buf, RK_SPL_HDR_START,
+					params->file_size - RK_SPL_HDR_START);
 }
 
 static int rksd_extract_subimage(void *buf,  struct image_tool_params *params)
diff --git a/tools/rkspi.c b/tools/rkspi.c
index 0271d2e..9fa43e8 100644
--- a/tools/rkspi.c
+++ b/tools/rkspi.c
@@ -49,8 +49,8 @@ static void rkspi_set_header(void *buf, struct stat *sbuf, int ifd,
 	       RK_SPL_HDR_SIZE);
 
 	if (rkcommon_need_rc4_spl(params))
-		rkcommon_rc4_encode_spl(buf, RK_SPL_START - 4,
-					params->file_size - RK_SPL_START + 4);
+		rkcommon_rc4_encode_spl(buf, RK_SPL_HDR_START,
+					params->file_size - RK_SPL_HDR_START);
 
 	/*
 	 * Spread the image out so we only use the first 2KB of each 4KB