diff --git a/utils/funcexp/func_makedate.cpp b/utils/funcexp/func_makedate.cpp
index 948b612de..5d013728f 100644
--- a/utils/funcexp/func_makedate.cpp
+++ b/utils/funcexp/func_makedate.cpp
@@ -149,9 +149,10 @@ uint64_t makedate(rowgroup::Row& row,
         case CalpontSystemCatalog::TIME:
         {
             std::ostringstream ss;
-            Time aTime = parm[1]->data()->getTimeIntVal(row, isNull);
-            ss << aTime.hour << aTime.minute << aTime.second;
-            dayofyear = ss.str();
+            char buf[9];
+            uint64_t aTime = parm[1]->data()->getTimeIntVal(row, isNull);
+            DataConvert::timeToString1(aTime, buf, 9);
+            dayofyear = buf;
             break;
         }
 
diff --git a/utils/funcexp/func_timediff.cpp b/utils/funcexp/func_timediff.cpp
index 742e8faf7..369bb80a1 100644
--- a/utils/funcexp/func_timediff.cpp
+++ b/utils/funcexp/func_timediff.cpp
@@ -118,6 +118,11 @@ string Func_timediff::getStrVal(rowgroup::Row& row,
 
         case execplan::CalpontSystemCatalog::TIME:
         case execplan::CalpontSystemCatalog::DATETIME:
+            if (type1 != type2)
+            {
+                isNull = true;
+                break;
+            }
             val1 = parm[0]->data()->getDatetimeIntVal(row, isNull);
             break;