diff --git a/gtsam/discrete/DiscreteFactor.h b/gtsam/discrete/DiscreteFactor.h
index a6356a045..2fe80a54c 100644
--- a/gtsam/discrete/DiscreteFactor.h
+++ b/gtsam/discrete/DiscreteFactor.h
@@ -144,7 +144,6 @@ class GTSAM_EXPORT DiscreteFactor : public Factor {
   /// Create new factor by maximizing over all values with the same separator.
   virtual DiscreteFactor::shared_ptr max(const Ordering& keys) const = 0;
 
-
   /**
    * Get the number of non-zero values contained in this factor.
    * It could be much smaller than `prod_{key}(cardinality(key))`.
diff --git a/gtsam/discrete/TableFactor.h b/gtsam/discrete/TableFactor.h
index 64e98c6a1..41b6287b8 100644
--- a/gtsam/discrete/TableFactor.h
+++ b/gtsam/discrete/TableFactor.h
@@ -17,6 +17,7 @@
 
 #pragma once
 
+#include <gtsam/discrete/DecisionTreeFactor.h>
 #include <gtsam/discrete/DiscreteFactor.h>
 #include <gtsam/discrete/DiscreteKey.h>
 #include <gtsam/discrete/Ring.h>
@@ -177,6 +178,8 @@ class GTSAM_EXPORT TableFactor : public DiscreteFactor {
       return apply(*tf, safe_div);
     } else if (auto dtf = std::dynamic_pointer_cast<DecisionTreeFactor>(f)) {
       return apply(TableFactor(f->discreteKeys(), *dtf), safe_div);
+    } else {
+      throw std::runtime_error("Unknown derived type for DiscreteFactor");
     }
   }