diff --git a/sklearn/preprocessing/data.py b/sklearn/preprocessing/data.py
index 42957133b654c..74099dc51b153 100644
--- a/sklearn/preprocessing/data.py
+++ b/sklearn/preprocessing/data.py
@@ -1584,6 +1584,10 @@ def transform(self, K, y=None, copy=True):
         K += self.K_fit_all_
 
         return K
+        
+    @property
+    def _pairwise(self):
+        return True
 
 
 def add_dummy_feature(X, value=1.0):