diff --git a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
index a428c760f45d4..7f26e6dd55121 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
@@ -23,7 +23,7 @@ import org.apache.spark.util.random.XORShiftRandom
 /**
  * Trait for a local matrix.
  */
-trait Matrix extends Serializable {
+sealed trait Matrix extends Serializable {
 
   /** Number of rows. */
   def numRows: Int
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala
index a45781d12e41e..6af225b7f49f7 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/linalg/Vectors.scala
@@ -33,7 +33,7 @@ import org.apache.spark.SparkException
  *
  * Note: Users should not implement this interface.
  */
-trait Vector extends Serializable {
+sealed trait Vector extends Serializable {
 
   /**
    * Size of the vector.