diff --git a/cores/common/base/lt_api.c b/cores/common/base/lt_api.c
index d8af241..7259fd0 100644
--- a/cores/common/base/lt_api.c
+++ b/cores/common/base/lt_api.c
@@ -149,11 +149,17 @@ bool lt_flash_erase_block(uint32_t offset) {
 }
 
 uint32_t lt_flash_read(uint32_t offset, uint8_t *data, size_t length) {
-	return fal_partition_read(fal_root_part, offset, data, length);
+	int ret = fal_partition_read(fal_root_part, offset, data, length);
+	if (ret == -1)
+		return 0;
+	return ret;
 }
 
 uint32_t lt_flash_write(uint32_t offset, const uint8_t *data, size_t length) {
-	return fal_partition_write(fal_root_part, offset, data, length);
+	int ret = fal_partition_write(fal_root_part, offset, data, length);
+	if (ret == -1)
+		return 0;
+	return ret;
 }
 
 /*__  __
diff --git a/platform.json b/platform.json
index e93ec23..4e21916 100644
--- a/platform.json
+++ b/platform.json
@@ -101,7 +101,7 @@
     },
     "tool-ltchiptool": {
       "type": "uploader",
-      "version": "https://github.com/libretuya/ltchiptool#v4.0.0a0",
+      "version": "https://github.com/libretuya/ltchiptool#v4.0.0a4",
       "version_prefix": true,
       "note": "This is used only for C/C++ code from ltchiptool."
     },