diff --git a/pregelix/pregelix-dataflow-std/src/main/java/edu/uci/ics/pregelix/dataflow/util/UpdateBuffer.java b/pregelix/pregelix-dataflow-std/src/main/java/edu/uci/ics/pregelix/dataflow/util/UpdateBuffer.java
index ea1e02e..49c5bb8 100644
--- a/pregelix/pregelix-dataflow-std/src/main/java/edu/uci/ics/pregelix/dataflow/util/UpdateBuffer.java
+++ b/pregelix/pregelix-dataflow-std/src/main/java/edu/uci/ics/pregelix/dataflow/util/UpdateBuffer.java
@@ -96,7 +96,7 @@
             fta.reset(buffer);
             for (int j = 0; j < fta.getTupleCount(); j++) {
                 tuple.reset(fta, j);
-                bta.update(tuple);
+                bta.upsert(tuple);
             }
         }