diff --git a/gtsam/nonlinear/ExpressionFactor.h b/gtsam/nonlinear/ExpressionFactor.h
index 53c183c91..c8137a098 100644
--- a/gtsam/nonlinear/ExpressionFactor.h
+++ b/gtsam/nonlinear/ExpressionFactor.h
@@ -52,6 +52,9 @@ public:
     initialize(expression);
   }
 
+  /// Destructor
+  virtual ~ExpressionFactor() {}
+
   /// print relies on Testable traits being defined for T
   void print(const std::string& s, const KeyFormatter& keyFormatter) const {
     NoiseModelFactor::print(s, keyFormatter);
@@ -161,47 +164,6 @@ private:
 // ExpressionFactor
 
 
-/**
- * ExpressionFactor variant that supports serialization
- * Simply overload the pure virtual method [expression] to construct an expression from keys_
- */
-template <typename T>
-class SerializableExpressionFactor : public ExpressionFactor<T> {
- public:
-  /// Constructor takes only two arguments, still need to call initialize
-  SerializableExpressionFactor(const SharedNoiseModel& noiseModel, const T& measurement)
-      : ExpressionFactor<T>(noiseModel, measurement) {
-  }
-
- protected:
-
-  /// Return an expression that predicts the measurement given Values
-  virtual Expression<T> expression() const = 0;
-
-  /// Default constructor, for serialization
-  SerializableExpressionFactor() {}
-
-  /// Save to an archive: just saves the base class
-  template <class Archive>
-  void save(Archive& ar, const unsigned int /*version*/) const {
-    ar << boost::serialization::make_nvp(
-              "ExpressionFactor", boost::serialization::base_object<ExpressionFactor<T> >(*this));
-  }
-
-  /// Load from an archive, creating a valid expression using the overloaded [expression] method
-  template <class Archive>
-  void load(Archive& ar, const unsigned int /*version*/) {
-    ar >> boost::serialization::make_nvp(
-              "ExpressionFactor", boost::serialization::base_object<ExpressionFactor<T> >(*this));
-    this->initialize(expression());
-  }
-
-  // Indicate that we implement save/load separately, and be friendly to boost
-  BOOST_SERIALIZATION_SPLIT_MEMBER()
-  friend class boost::serialization::access;
-};
-// SerializableExpressionFactor
-
 /// traits
 template <typename T>
 struct traits<ExpressionFactor<T> > : public Testable<ExpressionFactor<T> > {};
diff --git a/gtsam/nonlinear/SerializableExpressionFactor.h b/gtsam/nonlinear/SerializableExpressionFactor.h
new file mode 100644
index 000000000..09b4faa57
--- /dev/null
+++ b/gtsam/nonlinear/SerializableExpressionFactor.h
@@ -0,0 +1,75 @@
+/* ----------------------------------------------------------------------------
+
+ * GTSAM Copyright 2010, Georgia Tech Research Corporation, 
+ * Atlanta, Georgia 30332-0415
+ * All Rights Reserved
+ * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
+
+ * See LICENSE for the license information
+
+ * -------------------------------------------------------------------------- */
+
+/**
+ * @file SerializableExpressionFactor.h
+ * @date July 2015
+ * @author Frank Dellaert
+ * @brief ExpressionFactor variant that supports serialization
+ */
+
+#pragma once
+
+#include <gtsam/nonlinear/ExpressionFactor.h>
+
+namespace gtsam {
+
+/**
+ * ExpressionFactor variant that supports serialization
+ * Simply overload the pure virtual method [expression] to construct an expression from keys_
+ */
+template <typename T>
+class SerializableExpressionFactor : public ExpressionFactor<T> {
+ public:
+  /// Constructor takes only two arguments, still need to call initialize
+  SerializableExpressionFactor(const SharedNoiseModel& noiseModel, const T& measurement)
+      : ExpressionFactor<T>(noiseModel, measurement) {
+  }
+
+  /// Destructor
+  virtual ~SerializableExpressionFactor() {}
+
+ protected:
+
+  /// Return an expression that predicts the measurement given Values
+  virtual Expression<T> expression() const = 0;
+
+  /// Default constructor, for serialization
+  SerializableExpressionFactor() {}
+
+  /// Save to an archive: just saves the base class
+  template <class Archive>
+  void save(Archive& ar, const unsigned int /*version*/) const {
+    ar << boost::serialization::make_nvp(
+              "ExpressionFactor", boost::serialization::base_object<ExpressionFactor<T> >(*this));
+  }
+
+  /// Load from an archive, creating a valid expression using the overloaded [expression] method
+  template <class Archive>
+  void load(Archive& ar, const unsigned int /*version*/) {
+    ar >> boost::serialization::make_nvp(
+              "ExpressionFactor", boost::serialization::base_object<ExpressionFactor<T> >(*this));
+    this->initialize(expression());
+  }
+
+  // Indicate that we implement save/load separately, and be friendly to boost
+  BOOST_SERIALIZATION_SPLIT_MEMBER()
+  friend class boost::serialization::access;
+};
+// SerializableExpressionFactor
+
+/// traits
+template <typename T>
+struct traits<SerializableExpressionFactor<T> >
+    : public Testable<SerializableExpressionFactor<T> > {};
+
+}// \ namespace gtsam
+