diff --git a/GPy/core/model.py b/GPy/core/model.py
index c31ea209..2e70e7c2 100644
--- a/GPy/core/model.py
+++ b/GPy/core/model.py
@@ -458,7 +458,7 @@ class Model(Parameterized):
             numerical_gradient = (f1 - f2) / (2 * dx)
             global_ratio = (f1 - f2) / (2 * np.dot(dx, gradient))
 
-            return (np.abs(1. - global_ratio) < tolerance) or (np.abs(gradient - numerical_gradient).mean() - 1) < tolerance
+            return (np.abs(1. - global_ratio) < tolerance) or (np.abs(gradient - numerical_gradient).mean() < tolerance)
         else:
             # check the gradient of each parameter individually, and do some pretty printing
             try: