diff --git a/gtsam/linear/HessianFactor.cpp b/gtsam/linear/HessianFactor.cpp
index 06d2ece7b..8a9adf6f6 100644
--- a/gtsam/linear/HessianFactor.cpp
+++ b/gtsam/linear/HessianFactor.cpp
@@ -313,8 +313,9 @@ VectorValues HessianFactor::hessianDiagonal() const {
 /* ************************************************************************* */
 void HessianFactor::hessianDiagonalAdd(VectorValues &d) const {
   for (DenseIndex j = 0; j < (DenseIndex)size(); ++j) {
-    if(d.exists(keys_[j])) {
-      d.at(keys_[j]) += info_.diagonal(j);
+    auto item = d.find(keys_[j]);
+    if(item != d.end()) {
+      item->second += info_.diagonal(j);
     } else {
       d.emplace(keys_[j], info_.diagonal(j));
     }
diff --git a/gtsam/linear/JacobianFactor.cpp b/gtsam/linear/JacobianFactor.cpp
index 2e243c033..3f6eba5f3 100644
--- a/gtsam/linear/JacobianFactor.cpp
+++ b/gtsam/linear/JacobianFactor.cpp
@@ -560,8 +560,9 @@ void JacobianFactor::hessianDiagonalAdd(VectorValues& d) const {
         model_->whitenInPlace(column_k);
       dj(k) = dot(column_k, column_k);
     }
-    if(d.exists(j)) {
-      d.at(j) += dj;
+    auto item = d.find(j);
+    if(item != d.end()) {
+      item->second += dj;
     } else {
       d.emplace(j, dj);
     }