diff --git a/ezyrb/gpr.py b/ezyrb/gpr.py
index 5e515584..5837afa0 100644
--- a/ezyrb/gpr.py
+++ b/ezyrb/gpr.py
@@ -34,12 +34,17 @@ def __init__(self):
         self.Y_sample = None
         self.model = None
 
-    def fit(self, points, values, kern=None, optimization_restart=20):
+    def fit(self, points, values, kern=None, normalizer=True, optimization_restart=20):
         """
         Construct the regression given `points` and `values`.
 
         :param array_like points: the coordinates of the points.
         :param array_like values: the values in the points.
+        :param GPy.kern kern: kernel object from GPy.
+        :param bool normalizer: whether to normilize `values` or not.
+            Defaults to True.
+        :param int optimization_restart: number of restarts for the
+            optimization. Defaults to 20.
         """
         self.X_sample = np.array(points)
         self.Y_sample = np.array(values)
@@ -57,7 +62,7 @@ def fit(self, points, values, kern=None, optimization_restart=20):
             self.X_sample,
             self.Y_sample,
             kern,
-            normalizer=True)
+            normalizer=normalizer)
 
         self.model.optimize_restarts(optimization_restart, verbose=False)