diff --git a/lib/iris/tests/unit/util/test_array_equal.py b/lib/iris/tests/unit/util/test_array_equal.py
index 38b9652443..f63092587c 100644
--- a/lib/iris/tests/unit/util/test_array_equal.py
+++ b/lib/iris/tests/unit/util/test_array_equal.py
@@ -101,12 +101,15 @@ def test_string_arrays_0d_and_scalar(self):
         self.assertFalse(array_equal(array_a, "foobar."))
 
     def test_nan_equality_nan_ne_nan(self):
-        array = np.array([1.0, np.nan, 2.0, np.nan, 3.0])
-        self.assertFalse(array_equal(array, array))
+        array_a = np.array([1.0, np.nan, 2.0, np.nan, 3.0])
+        array_b = array_a.copy()
+        self.assertFalse(array_equal(array_a, array_a))
+        self.assertFalse(array_equal(array_a, array_b))
 
     def test_nan_equality_nan_naneq_nan(self):
         array_a = np.array([1.0, np.nan, 2.0, np.nan, 3.0])
         array_b = np.array([1.0, np.nan, 2.0, np.nan, 3.0])
+        self.assertTrue(array_equal(array_a, array_a, withnans=True))
         self.assertTrue(array_equal(array_a, array_b, withnans=True))
 
     def test_nan_equality_nan_nanne_a(self):