diff --git a/gtsam/discrete/DecisionTreeFactor.cpp b/gtsam/discrete/DecisionTreeFactor.cpp
index 19d61c3b1..ff4c0694e 100644
--- a/gtsam/discrete/DecisionTreeFactor.cpp
+++ b/gtsam/discrete/DecisionTreeFactor.cpp
@@ -135,33 +135,31 @@ namespace gtsam {
   }
 
   /* ************************************************************************* */
-  // Check markdown representation looks as expected.
-  std::string DecisionTreeFactor::_repr_markdown_() const {
+  std::string DecisionTreeFactor::_repr_markdown_(
+      const KeyFormatter& keyFormatter) const {
     std::stringstream ss;
 
-    // Print out header and calculate number of rows.
+    // Print out header and construct argument for `cartesianProduct`.
+    std::vector<std::pair<Key, size_t>> pairs;
     ss << "|";
-    for (auto& key : cardinalities_) {
-      size_t k = key.second;
-      ss << key.first << "(" << k << ")|";
+    for (auto& key : keys()) {
+      ss << keyFormatter(key) << "|";
+      pairs.emplace_back(key, cardinalities_.at(key));
     }
     ss << "value|\n";
 
     // Print out separator with alignment hints.
-    size_t n = cardinalities_.size();
     ss << "|";
-    for (size_t j = 0; j < n; j++) ss << ":-:|";
+    for (size_t j = 0; j < size(); j++) ss << ":-:|";
     ss << ":-:|\n";
 
     // Print out all rows.
-    std::vector<std::pair<Key, size_t>> keys(cardinalities_.begin(),
-                                             cardinalities_.end());
-    const auto assignments = cartesianProduct(keys);
-    for (auto &&assignment : assignments) {
+    std::vector<std::pair<Key, size_t>> rpairs(pairs.rbegin(), pairs.rend());
+    const auto assignments = cartesianProduct(rpairs);
+    for (const auto& assignment : assignments) {
       ss << "|";
-      for (auto& kv : assignment) ss << kv.second << "|";
-      const double value = operator()(assignment);
-      ss << value << "|\n";
+      for (auto& key : keys()) ss << assignment.at(key) << "|";
+      ss << operator()(assignment) << "|\n";
     }
     return ss.str();
   }
diff --git a/gtsam/discrete/DecisionTreeFactor.h b/gtsam/discrete/DecisionTreeFactor.h
index 68d629e9c..308b2f9ca 100644
--- a/gtsam/discrete/DecisionTreeFactor.h
+++ b/gtsam/discrete/DecisionTreeFactor.h
@@ -167,7 +167,8 @@ namespace gtsam {
     /// @{
     
     /// Render as markdown table.
-    std::string _repr_markdown_() const;
+    std::string _repr_markdown_(
+        const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;
 
     /// @}
 
diff --git a/gtsam/discrete/tests/testDecisionTreeFactor.cpp b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
index 3026d5f82..75d5efa9f 100644
--- a/gtsam/discrete/tests/testDecisionTreeFactor.cpp
+++ b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
@@ -83,19 +83,21 @@ TEST( DecisionTreeFactor, sum_max)
 }
 
 /* ************************************************************************* */
+// Check markdown representation looks as expected.
 TEST(DecisionTreeFactor, markdown) {
-  DiscreteKey v0(0, 3), v1(1, 2);
-  DecisionTreeFactor f1(v0 & v1, "1 2  3 4  5 6");
+  DiscreteKey A(12, 3), B(5, 2);
+  DecisionTreeFactor f1(A & B, "1 2  3 4  5 6");
   string expected =
-      "|0(3)|1(2)|value|\n"
+      "|A|B|value|\n"
       "|:-:|:-:|:-:|\n"
       "|0|0|1|\n"
-      "|1|0|3|\n"
-      "|2|0|5|\n"
       "|0|1|2|\n"
+      "|1|0|3|\n"
       "|1|1|4|\n"
+      "|2|0|5|\n"
       "|2|1|6|\n";
-  string actual = f1._repr_markdown_();
+  auto formatter = [](Key key) { return key == 12 ? "A" : "B"; };
+  string actual = f1._repr_markdown_(formatter);
   EXPECT(actual == expected);
 }