diff --git a/GPy/kern/linear.py b/GPy/kern/linear.py
index 459b5a71..bc94b79d 100644
--- a/GPy/kern/linear.py
+++ b/GPy/kern/linear.py
@@ -21,7 +21,7 @@ class linear(kernpart):
     :rtype: kernel object
     """
 
-    def __init__(self,D,variances=None,ARD=True):
+    def __init__(self,D,variances=None,ARD=False):
         self.D = D
         self.ARD = ARD
         if ARD == False:
diff --git a/GPy/kern/rbf.py b/GPy/kern/rbf.py
index 68fa5f55..082bbe7f 100644
--- a/GPy/kern/rbf.py
+++ b/GPy/kern/rbf.py
@@ -75,6 +75,7 @@ class rbf(kernpart):
     def K(self,X,X2,target):
         if X2 is None:
             X2 = X
+
         self._K_computations(X,X2)
         np.add(self.variance*self._K_dvar, target,target)