diff --git a/src/test/kotlin/g3401_3500/s3446_sort_matrix_by_diagonals/SolutionTest.kt b/src/test/kotlin/g3401_3500/s3446_sort_matrix_by_diagonals/SolutionTest.kt
index baa32b562..064a75c0f 100644
--- a/src/test/kotlin/g3401_3500/s3446_sort_matrix_by_diagonals/SolutionTest.kt
+++ b/src/test/kotlin/g3401_3500/s3446_sort_matrix_by_diagonals/SolutionTest.kt
@@ -9,7 +9,7 @@ internal class SolutionTest {
     fun sortMatrix() {
         assertThat<Array<IntArray>>(
             Solution().sortMatrix(arrayOf<IntArray>(intArrayOf(1, 7, 3), intArrayOf(9, 8, 2), intArrayOf(4, 5, 6))),
-            equalTo<Array<IntArray>?>(
+            equalTo<Array<IntArray>>(
                 arrayOf<IntArray>(
                     intArrayOf(8, 2, 3),
                     intArrayOf(9, 6, 7),
@@ -21,17 +21,17 @@ internal class SolutionTest {
 
     @Test
     fun sortMatrix2() {
-        assertThat<Array<IntArray>?>(
+        assertThat<Array<IntArray>>(
             Solution().sortMatrix(arrayOf<IntArray>(intArrayOf(0, 1), intArrayOf(1, 2))),
-            equalTo<Array<IntArray>?>(arrayOf<IntArray>(intArrayOf(2, 1), intArrayOf(1, 0))),
+            equalTo<Array<IntArray>>(arrayOf<IntArray>(intArrayOf(2, 1), intArrayOf(1, 0))),
         )
     }
 
     @Test
     fun sortMatrix3() {
-        assertThat<Array<IntArray>?>(
+        assertThat<Array<IntArray>>(
             Solution().sortMatrix(arrayOf<IntArray>(intArrayOf(1))),
-            equalTo<Array<IntArray>?>(arrayOf<IntArray>(intArrayOf(1))),
+            equalTo<Array<IntArray>>(arrayOf<IntArray>(intArrayOf(1))),
         )
     }
 }