diff --git a/gtsam/inference/VariableIndex-inl.h b/gtsam/inference/VariableIndex-inl.h
index 727ef8fd8..adfd68671 100644
--- a/gtsam/inference/VariableIndex-inl.h
+++ b/gtsam/inference/VariableIndex-inl.h
@@ -24,8 +24,7 @@ namespace gtsam {
 
 /* ************************************************************************* */
 template<class FG>
-void VariableIndex::augment(const FG& factors,
-    boost::optional<const FactorIndices&> newFactorIndices) {
+void VariableIndex::augment(const FG& factors, const FactorIndices* newFactorIndices) {
   gttic(VariableIndex_augment);
 
   // Augment index for each factor
diff --git a/gtsam/inference/VariableIndex.h b/gtsam/inference/VariableIndex.h
index 47438ecd6..f934a72af 100644
--- a/gtsam/inference/VariableIndex.h
+++ b/gtsam/inference/VariableIndex.h
@@ -126,7 +126,16 @@ class GTSAM_EXPORT VariableIndex {
    * solving problems incrementally.
    */
   template<class FG>
-  void augment(const FG& factors, boost::optional<const FactorIndices&> newFactorIndices = boost::none);
+  void augment(const FG& factors, const FactorIndices* newFactorIndices = nullptr);
+
+  /**
+   * An overload of augment() that takes a single factor. and l-value
+   * reference to FactorIndeces.
+   */
+  template<class FG>
+  void augment(const FG& factor, const FactorIndices& newFactorIndices) {
+    augment(factor, &newFactorIndices);
+  }
 
   /**
    * Augment the variable index after an existing factor now affects to more