diff --git a/src/common/inc/tdataformat.h b/src/common/inc/tdataformat.h
index ba9196c52a4f1a37698461a74f198ea4c7d186a6..f8cc374eb00e953ce307070f27a585146f5bc6da 100644
--- a/src/common/inc/tdataformat.h
+++ b/src/common/inc/tdataformat.h
@@ -560,6 +560,8 @@ static FORCE_INLINE int tdAddColToKVRow(SKVRowBuilder *pBuilder, int16_t colId,
   char* jumpType = (char*)value;
   if(isJumpJsonVType) jumpType += CHAR_BYTES;
   int tlen = IS_VAR_DATA_TYPE(type) ? varDataTLen(jumpType) : TYPE_BYTES[type];
+  if(isJumpJsonVType) tlen += CHAR_BYTES;   // add type size
+
   if (tlen > pBuilder->alloc - pBuilder->size) {
     while (tlen > pBuilder->alloc - pBuilder->size) {
       pBuilder->alloc *= 2;