diff --git a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRanking.java b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRanking.java
index 978c9e134c..6f5f5e60b2 100644
--- a/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRanking.java
+++ b/commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRanking.java
@@ -21,6 +21,7 @@
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.commons.rng.UniformRandomProvider;
 import org.apache.commons.rng.simple.RandomSource;
@@ -158,8 +159,8 @@ public NaturalRanking(NaNStrategy nanStrategy,
     private NaturalRanking(NaNStrategy nanStrategy,
                            TiesStrategy tiesStrategy,
                            UniformRandomProvider random) {
-        this.nanStrategy = nanStrategy;
-        this.tiesStrategy = tiesStrategy;
+        this.nanStrategy = Objects.requireNonNull(nanStrategy, "nanStrategy");
+        this.tiesStrategy = Objects.requireNonNull(tiesStrategy, "tiesStrategy");
         this.random = random;
     }
 
diff --git a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRankingTest.java b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRankingTest.java
index 5f4c512844..e53cc433c1 100644
--- a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRankingTest.java
+++ b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/stat/ranking/NaturalRankingTest.java
@@ -279,4 +279,18 @@ public void testNoNaNsFailed() {
         double[] ranks = ranking.rank(data);
         TestUtils.assertEquals(data, ranks, 0d);
     }
+
+    /**
+     * Tests NaturalRanking constructor with null strategies as inputs.
+     * These should be switched to the default strategies.
+     */
+    @Test
+    public void testNullStrategies() {
+        Assert.assertThrows(NullPointerException.class, () -> {
+            new NaturalRanking((NaNStrategy) null, (TiesStrategy) null);
+        });
+        Assert.assertThrows(NullPointerException.class, () -> {
+            new NaturalRanking(NaturalRanking.DEFAULT_NAN_STRATEGY, (TiesStrategy) null);
+        });
+    }
 }