diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index f6d2fdadaea0e05e5d45c98193e57f809f093d07..f985cc324d809cd0937e2d886dfff55c1f29b2e3 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -1268,7 +1268,7 @@ static bool validateMinuteRange(int8_t hour, int8_t minute, char sign) {
 }
 
 static bool validateTimestampDigits(const SValueNode* pVal) {
-  if (IS_INTEGER_TYPE(pVal->node.resType.type)) {
+  if (!IS_INTEGER_TYPE(pVal->node.resType.type)) {
     return false;
   }
 
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index d335b04ea474bb41e4d09c89b946866e8b919f30..a5154fac398cc2d0ebcf55c8ccbcfaa954559cbc 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -856,10 +856,13 @@ int32_t castFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutp
 int32_t toISO8601Function(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput) {
   int32_t type = GET_PARAM_TYPE(pInput);
 
+  bool tzPresent = (inputNum == 2) ? true : false;
   char* tz;
   int32_t tzLen;
-  tz = varDataVal(pInput[1].columnData->pData);
-  tzLen = varDataLen(pInput[1].columnData->pData);
+  if (tzPresent) {
+    tz = varDataVal(pInput[1].columnData->pData);
+    tzLen = varDataLen(pInput[1].columnData->pData);
+  }
 
   for (int32_t i = 0; i < pInput[0].numOfRows; ++i) {
     if (colDataIsNull_s(pInput[0].columnData, i)) {