diff --git a/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/operators/std/UnnestRuntimeFactory.java b/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/operators/std/UnnestRuntimeFactory.java
index d402518..81f0afa 100644
--- a/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/operators/std/UnnestRuntimeFactory.java
+++ b/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/operators/std/UnnestRuntimeFactory.java
@@ -86,7 +86,7 @@
             private IUnnestingEvaluator agg;
             private ArrayTupleBuilder tupleBuilder;
 
-            private int tupleCount = 1;
+            private int tupleCount;
             private IScalarEvaluator offsetEval = posOffsetEvalFactory.createScalarEvaluator(ctx);
 
             @Override
@@ -98,6 +98,7 @@
                     throw new HyracksDataException(ae);
                 }
                 tupleBuilder = new ArrayTupleBuilder(projectionList.length);
+                tupleCount = 1;
                 writer.open();
             }