diff --git a/velox/functions/sparksql/aggregates/DecimalSumAggregate.h b/velox/functions/sparksql/aggregates/DecimalSumAggregate.h
index 2ea6561f66089..4048e5c57742f 100644
--- a/velox/functions/sparksql/aggregates/DecimalSumAggregate.h
+++ b/velox/functions/sparksql/aggregates/DecimalSumAggregate.h
@@ -130,11 +130,11 @@ class DecimalSumAggregate : public exec::Aggregate {
 
     for (auto i = 0; i < numGroups; ++i) {
       char* group = groups[i];
+      clearNull(rawNulls, i);
       if (isNull(group)) {
         rawSums[i] = 0;
         bits::setBit(rawIsEmpty, i, true);
       } else {
-        clearNull(rawNulls, i);
         auto* decimalSum = accumulator(group);
         bool overflow = false;
         auto result = (TResultType)computeFinalValue(decimalSum, overflow);