diff --git a/stocproc/stocproc.py b/stocproc/stocproc.py
index 9b6c24f..e4d6b8a 100644
--- a/stocproc/stocproc.py
+++ b/stocproc/stocproc.py
@@ -95,7 +95,7 @@ class StocProc(abc.ABC):
         self.t_max = t_max
         self.num_grid_points = num_grid_points
         self.t = np.linspace(0, t_max, num_grid_points)
-
+        self.key = "generic"
         self._z = None
         self._interpolator = None
         self._interpolator_dot = None