diff --git a/GPy/util/normalizer.py b/GPy/util/normalizer.py
index 07716bc9..83c79b32 100644
--- a/GPy/util/normalizer.py
+++ b/GPy/util/normalizer.py
@@ -91,8 +91,8 @@ class Standardize(_Norm):
         self.mean = Y.mean(0).view(np.ndarray)
         self.std = Y.std(0).view(np.ndarray)
         if np.any(self.std == 0):
-            self.std[np.where(Y_std==0)]=1.
             warnings.warn("Some values of Y have standard deviation of zero. Resetting to 1.0 to avoid divide by zero errors.")
+            self.std[np.where(self.std==0)]=1.
 
     def normalize(self, Y):
         super(Standardize, self).normalize(Y)