diff --git a/src/main/java/kyu6/TribonacciSequence.java b/src/main/java/kyu6/TribonacciSequence.java
index a8749d1..2438955 100644
--- a/src/main/java/kyu6/TribonacciSequence.java
+++ b/src/main/java/kyu6/TribonacciSequence.java
@@ -5,6 +5,7 @@
 public class TribonacciSequence {
 
     private static final int SIGNATURE_SIZE = 3;
+    private static final int MAX_SEQUENCE_LENGTH = 1_000_000;
 
     //6 https://www.codewars.com/kata/556deca17c58da83c00002db
 
@@ -12,8 +13,10 @@ public static double[] tribonacci(double[] s, int n) {
         if (s == null || s.length != SIGNATURE_SIZE) {
             throw new IllegalArgumentException("signature must contain exactly three values");
         }
-        if (n < 0) {
-            throw new IllegalArgumentException("sequence length must not be negative");
+        if (n < 0 || n > MAX_SEQUENCE_LENGTH) {
+            throw new IllegalArgumentException(
+                    "sequence length must be between 0 and " + MAX_SEQUENCE_LENGTH
+            );
         }
         double[] result = new double[n];
         int signatureLength = Math.min(SIGNATURE_SIZE, n);
diff --git a/src/test/java/kyu6/TribonacciSequenceTest.java b/src/test/java/kyu6/TribonacciSequenceTest.java
index c308ca7..34e022b 100644
--- a/src/test/java/kyu6/TribonacciSequenceTest.java
+++ b/src/test/java/kyu6/TribonacciSequenceTest.java
@@ -31,5 +31,9 @@ void shouldRejectInvalidSignatureAndLength() {
         assertThrows(IllegalArgumentException.class, () -> TribonacciSequence.tribonacci(null, 1));
         assertThrows(IllegalArgumentException.class, () -> TribonacciSequence.tribonacci(new double[]{1, 1}, 2));
         assertThrows(IllegalArgumentException.class, () -> TribonacciSequence.tribonacci(new double[]{1, 1, 1}, -1));
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> TribonacciSequence.tribonacci(new double[]{1, 1, 1}, Integer.MAX_VALUE)
+        );
     }
 }