diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 13e1582526147b23928af8ead07711b873bc1a53..b6fe38e5c2366c89f121a3024c4718b1d881911f 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -655,7 +655,7 @@ static void trimDataBlock(void* pDataBlock, STableDataBlocks* pTableDataBlock) {
 
     int toffset = 0;
     for (int32_t j = 0; j < tinfo.numOfColumns; j++) {
-      tdAppendColVal(trow, p, pSchema[j].type, pSchema[j].bytes, toffset);
+      tdAppendColVal(trow, isNull(p, pSchema[j].type) ? NULL : p, pSchema[j].type, pSchema[j].bytes, toffset);
       toffset += TYPE_BYTES[pSchema[j].type];
       p += pSchema[j].bytes;
     }