diff --git a/dbcon/joblist/tupleaggregatestep.cpp b/dbcon/joblist/tupleaggregatestep.cpp
index be0e2009d..0f981e68f 100644
--- a/dbcon/joblist/tupleaggregatestep.cpp
+++ b/dbcon/joblist/tupleaggregatestep.cpp
@@ -1505,10 +1505,17 @@ void TupleAggregateStep::prep1PhaseAggregate(
                 typeAgg.push_back(typeProj[colProj]);
                 widthAgg.push_back(width[colProj]);
                 // If the param is const
-                ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
-                if (cc)
+                if (udafc)
                 {
-                    funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                    ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
+                    if (cc)
+                    {
+                        funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                    }
+                }
+                else
+                {
+                    throw QueryDataExcept("prep1PhaseAggregate: UDAF multi function with no parms", aggregateFuncErr);
                 }
                 ++udafcParamIdx;
             }
@@ -2123,10 +2130,17 @@ void TupleAggregateStep::prep1PhaseDistinctAggregate(
                     multiParmIndexes.push_back(colAgg);
                     ++colAgg;
                     // If the param is const
-                    ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
-                    if (cc)
+                    if (udafc)
                     {
-                        funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
+                        if (cc)
+                        {
+                            funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        }
+                    }
+                    else
+                    {
+                        throw QueryDataExcept("prep1PhaseDistinctAggregate: UDAF multi function with no parms", aggregateFuncErr);
                     }
                     ++udafcParamIdx;
                 }
@@ -3398,10 +3412,17 @@ void TupleAggregateStep::prep2PhasesAggregate(
                     widthAggPm.push_back(width[colProj]);
                     colAggPm++;
                     // If the param is const
-                    ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
-                    if (cc)
+                    if (udafc)
                     {
-                        funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
+                        if (cc)
+                        {
+                            funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        }
+                    }
+                    else
+                    {
+                        throw QueryDataExcept("prep2PhasesAggregate: UDAF multi function with no parms", aggregateFuncErr);
                     }
                     ++udafcParamIdx;
                 }
@@ -4257,10 +4278,17 @@ void TupleAggregateStep::prep2PhasesDistinctAggregate(
                     multiParmIndexes.push_back(colAggPm);
                     colAggPm++;
                     // If the param is const
-                    ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
-                    if (cc)
+                    if (udafc)
                     {
-                        funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        ConstantColumn* cc = dynamic_cast<ConstantColumn*>(udafc->aggParms()[udafcParamIdx].get());
+                        if (cc)
+                        {
+                            funct->fpConstCol = udafc->aggParms()[udafcParamIdx];
+                        }
+                    }
+                    else
+                    {
+                        throw QueryDataExcept("prep2PhasesDistinctAggregate: UDAF multi function with no parms", aggregateFuncErr);
                     }
                     ++udafcParamIdx;
                 }
diff --git a/dbcon/mysql/ha_calpont_execplan.cpp b/dbcon/mysql/ha_calpont_execplan.cpp
index d030d1855..8df06c6b4 100644
--- a/dbcon/mysql/ha_calpont_execplan.cpp
+++ b/dbcon/mysql/ha_calpont_execplan.cpp
@@ -4165,7 +4165,7 @@ ReturnedColumn* buildAggregateColumn(Item* item, gp_walk_info& gwi)
         rowCol->columnVec(selCols);
         (dynamic_cast<GroupConcatColumn*>(ac))->orderCols(orderCols);
         parm.reset(rowCol);
-            ac->aggParms().push_back(parm);
+        ac->aggParms().push_back(parm);
 
         if (gc->str_separator())
         {
@@ -4311,15 +4311,15 @@ ReturnedColumn* buildAggregateColumn(Item* item, gp_walk_info& gwi)
                     gwi.parseErrorText = IDBErrorInfo::instance()->errorMsg(ERR_NON_SUPPORT_AGG_ARGS, args);
                 }
 
-                    if (ac)
-                        delete ac;
+                if (ac)
+                    delete ac;
                 return NULL;
             }
-                if (parm)
-                {
-                    // MCOL-1201 multi-argument aggregate
-                    ac->aggParms().push_back(parm);
-                }
+            if (parm)
+            {
+                // MCOL-1201 multi-argument aggregate
+                ac->aggParms().push_back(parm);
+            }
         }
     }
 
@@ -10033,7 +10033,15 @@ int getGroupPlan(gp_walk_info& gwi, SELECT_LEX& select_lex, SCSEP& csep, cal_gro
             return ER_CHECK_NOT_IMPLEMENTED;
         }
 
-        (*coliter)->aggParms().push_back(minSc);
+        // Replace the last (presumably constant) object with minSc
+        if ((*coliter)->aggParms().empty())
+        {
+            (*coliter)->aggParms().push_back(minSc);
+        }
+        else
+        {
+            (*coliter)->aggParms()[0] = minSc;
+        }
     }
 
     std::vector<FunctionColumn*>::iterator funciter;