diff --git a/utils/joiner/tuplejoiner.cpp b/utils/joiner/tuplejoiner.cpp
index 671e63466..b8dc2937f 100644
--- a/utils/joiner/tuplejoiner.cpp
+++ b/utils/joiner/tuplejoiner.cpp
@@ -131,7 +131,7 @@ TupleJoiner::TupleJoiner(
 	cpValues.reset(new vector<int64_t>[smallKeyColumns.size()]);
 	for (uint32_t i = 0; i < smallKeyColumns.size(); i++) {
 		discreteValues[i] = false;
-        if (isUnsigned(smallRG.getColType(i)))
+        if (isUnsigned(smallRG.getColTypes()[smallKeyColumns[i]]))
         {
             cpValues[i].push_back(static_cast<int64_t>(numeric_limits<uint64_t>::max()));
             cpValues[i].push_back(0);
@@ -859,7 +859,7 @@ boost::shared_ptr<TupleJoiner> TupleJoiner::copyForDiskJoin()
 	ret->cpValues.reset(new vector<int64_t>[smallKeyColumns.size()]);
 	for (uint32_t i = 0; i < smallKeyColumns.size(); i++) {
 		ret->discreteValues[i] = false;
-        if (isUnsigned(smallRG.getColType(i)))
+        if (isUnsigned(smallRG.getColTypes()[smallKeyColumns[i]]))
         {
             ret->cpValues[i].push_back(static_cast<int64_t>(numeric_limits<uint64_t>::max()));
             ret->cpValues[i].push_back(0);