diff --git a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/tipremove/TipAddVertex.java b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/tipremove/TipAddVertex.java
index 8e77a0a..7b695dc 100644
--- a/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/tipremove/TipAddVertex.java
+++ b/genomix/genomix-pregelix/src/main/java/edu/uci/ics/genomix/pregelix/operator/tipremove/TipAddVertex.java
@@ -87,7 +87,7 @@
                  * set the vertex value
                  */
                 KmerListWritable kmerList = new KmerListWritable(kmerSize);
-                kmerList.append(vertexId);
+                kmerList.append(getVertexId());
                 vertexValue.setRFList(kmerList);
                 vertexValue.setKmer(vertexId);
                 vertex.setVertexValue(vertexValue);