diff --git a/src/tsdb/src/tsdbFS.c b/src/tsdb/src/tsdbFS.c
index 157806706786617cd88776314dfbe5907fcc72e4..7f26f06fff09ef8d6c1842d139b0a04d4fa58a0f 100644
--- a/src/tsdb/src/tsdbFS.c
+++ b/src/tsdb/src/tsdbFS.c
@@ -102,8 +102,8 @@ static int tsdbDecodeDFileSetArray(void **originBuf, void *buf, SArray *pArray,
   if (pSFSHeader->version == TSDB_FS_VER_0) {
     uint64_t extendedSize = pSFSHeader->len + nset * TSDB_FILE_MAX * sizeof(TSDB_FVER_TYPE);
     if (taosTSizeof(*originBuf) < extendedSize) {
-      size_t ptrDistance = (size_t)POINTER_DISTANCE(buf, *originBuf);
-      if (tsdbMakeRoom(originBuf, extendedSize) < 0) {
+      size_t ptrDistance = POINTER_DISTANCE(buf, *originBuf);
+      if (tsdbMakeRoom(originBuf, (size_t)extendedSize) < 0) {
         terrno = TSDB_CODE_FS_OUT_OF_MEMORY;
         return -1;
       }