diff --git a/pymc_extras/statespace/core/statespace.py b/pymc_extras/statespace/core/statespace.py
index e62d345f..92ca4e9e 100644
--- a/pymc_extras/statespace/core/statespace.py
+++ b/pymc_extras/statespace/core/statespace.py
@@ -257,6 +257,7 @@ def __init__(
         self.kalman_smoother = KalmanSmoother()
         self.make_symbolic_graph()
 
+        self.requirement_table = None
         self._populate_prior_requirements()
         self._populate_data_requirements()