diff --git a/gtsam/slam/dataset.cpp b/gtsam/slam/dataset.cpp
index db85c65bf..607819cc7 100644
--- a/gtsam/slam/dataset.cpp
+++ b/gtsam/slam/dataset.cpp
@@ -163,7 +163,7 @@ static SharedNoiseModel readNoiseModel(ifstream& is, bool smart,
 }
 
 /* ************************************************************************* */
-GraphAndValues load2D(const string& filename, SharedNoiseModel model, int maxID,
+GraphAndValues load2D(const string& filename, SharedNoiseModel model, Key maxID,
     bool addNoise, bool smart, NoiseFormat noiseFormat,
     KernelFunctionType kernelFunctionType) {
 
@@ -211,7 +211,7 @@ GraphAndValues load2D(const string& filename, SharedNoiseModel model, int maxID,
   }
 
   // Parse the pose constraints
-  int id1, id2;
+  Key id1, id2;
   bool haveLandmark = false;
   while (!is.eof()) {
     if (!(is >> tag))
diff --git a/gtsam/slam/dataset.h b/gtsam/slam/dataset.h
index c27419a6e..09a5baac7 100644
--- a/gtsam/slam/dataset.h
+++ b/gtsam/slam/dataset.h
@@ -94,7 +94,7 @@ GTSAM_EXPORT GraphAndValues load2D(
  * @return graph and initial values
  */
 GTSAM_EXPORT GraphAndValues load2D(const std::string& filename,
-    SharedNoiseModel model = SharedNoiseModel(), int maxID = 0, bool addNoise =
+    SharedNoiseModel model = SharedNoiseModel(), Key maxID = 0, bool addNoise =
         false, bool smart = true, NoiseFormat noiseFormat = NoiseFormatGRAPH, //
     KernelFunctionType kernelFunctionType = KernelFunctionTypeNONE);