diff --git a/mllib/src/test/scala/org/apache/spark/ml/classification/DecisionTreeClassifierSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/classification/DecisionTreeClassifierSuite.scala
index baf6b9083900f2c5493d5dc76c9a948b67d232c8..9169bcd390dce9d0e5dffb531a3dd2674b1bc387 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/classification/DecisionTreeClassifierSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/classification/DecisionTreeClassifierSuite.scala
@@ -305,7 +305,11 @@ class DecisionTreeClassifierSuite extends SparkFunSuite with MLlibTestSparkConte
         n.split match {
           case s: CategoricalSplit =>
             assert(s.leftCategories === Array(1.0))
+          case other =>
+            fail(s"All splits should be categorical, but got ${other.getClass.getName}: $other.")
         }
+      case other =>
+        fail(s"Root node should be an internal node, but got ${other.getClass.getName}: $other.")
     }
   }
 
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/fpm/FPGrowthSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/fpm/FPGrowthSuite.scala
index b9e997c207bc70689905b683c7556814d77819e9..dc44c58e97eb4f9660e2a65191be2ddf012e34dc 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/fpm/FPGrowthSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/fpm/FPGrowthSuite.scala
@@ -16,6 +16,8 @@
  */
 package org.apache.spark.mllib.fpm
 
+import scala.language.existentials
+
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.mllib.util.MLlibTestSparkContext
 import org.apache.spark.util.Utils