diff --git a/GPy/testing/cython_tests.py b/GPy/testing/cython_tests.py
index 6c8c4c0f..f88f12f3 100644
--- a/GPy/testing/cython_tests.py
+++ b/GPy/testing/cython_tests.py
@@ -9,7 +9,7 @@ These tests make sure that the opure python and cython codes work the same
 
 class CythonTestChols(np.testing.TestCase):
     def setUp(self):
-        self.flat = np.random.randn(5,45)
+        self.flat = np.random.randn(45,5)
         self.triang = np.array([np.eye(20) for i in range(3)])
     def test_flat_to_triang(self):
         L1 = choleskies._flat_to_triang_pure(self.flat)