diff --git a/GPy/kern/_src/kernel_slice_operations.py b/GPy/kern/_src/kernel_slice_operations.py
index de4aa629..8c06d0c0 100644
--- a/GPy/kern/_src/kernel_slice_operations.py
+++ b/GPy/kern/_src/kernel_slice_operations.py
@@ -26,6 +26,7 @@ class KernCallsViaSlicerMeta(ParametersChangedMeta):
         put_clean(dct, 'psi0', _slice_psi)
         put_clean(dct, 'psi1', _slice_psi)
         put_clean(dct, 'psi2', _slice_psi)
+        put_clean(dct, 'psi2n', _slice_psi)
         put_clean(dct, 'update_gradients_expectations', _slice_update_gradients_expectations)
         put_clean(dct, 'gradients_Z_expectations', _slice_gradients_Z_expectations)
         put_clean(dct, 'gradients_qX_expectations', _slice_gradients_qX_expectations)
diff --git a/GPy/util/caching.py b/GPy/util/caching.py
index 196ce343..65f608bf 100644
--- a/GPy/util/caching.py
+++ b/GPy/util/caching.py
@@ -76,7 +76,7 @@ class Cacher(object):
         self.order.append(cache_id)
         self.cached_inputs[cache_id] = inputs
         for a in inputs:
-            if a is not None:
+            if a is not None and not isinstance(a, int):
                 ind_id = self.id(a)
                 v = self.cached_input_ids.get(ind_id, [weakref.ref(a), []])
                 v[1].append(cache_id)
@@ -103,9 +103,9 @@ class Cacher(object):
         inputs = self.combine_inputs(args, kw, self.ignore_args)
         cache_id = self.prepare_cache_id(inputs)
         # 2: if anything is not cachable, we will just return the operation, without caching
-        if reduce(lambda a, b: a or (not (isinstance(b, Observable) or b is None)), inputs, False):
-            #print 'WARNING: '+self.operation.__name__ + ' not cacheable!'
-            #print [not (isinstance(b, Observable)) for b in inputs]
+        if reduce(lambda a, b: a or (not (isinstance(b, Observable) or b is None or isinstance(b,int))), inputs, False):
+#             print 'WARNING: '+self.operation.__name__ + ' not cacheable!'
+#             print [not (isinstance(b, Observable)) for b in inputs]
             return self.operation(*args, **kw)
         # 3&4: check whether this cache_id has been cached, then has it changed?
         try: