diff --git a/README.md b/README.md
index 68852a4..bb4343b 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,4 @@ Follow the step if you want to test SGraph:
 
 3. Replace `$SPARK_HOME$/bin/compute-classpath.sh` with `configs/compute-classpath.sh`
 
-4. Make `org.apache.spark.util.collection.PrimitiveVector` extends Serializable
-
-5. Recompile Spark
+4. Recompile Spark