diff --git a/source/libs/parser/src/parTranslater.c b/source/libs/parser/src/parTranslater.c
index 3c3c0e4a61..52abeadac9 100644
--- a/source/libs/parser/src/parTranslater.c
+++ b/source/libs/parser/src/parTranslater.c
@@ -3214,7 +3214,7 @@ static int32_t checkAlterSuperTable(STranslateContext* pCxt, SAlterTableStmt* pS
       if (NULL == pSchema) {
         code = generateSyntaxErrMsg(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_COLUMN, pStmt->colName);
       } else if (!IS_VAR_DATA_TYPE(pSchema->type) || pSchema->type != pStmt->dataType.type ||
-                 pSchema->bytes >= pStmt->dataType.bytes) {
+                 pSchema->bytes >= calcTypeBytes(pStmt->dataType)) {
         code = generateSyntaxErrMsg(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_MODIFY_COL);
       }
     }