diff --git a/gtsam/constrained/NonlinearConstraint.h b/gtsam/constrained/NonlinearConstraint.h
index a01430bf3..f64e8bfc1 100644
--- a/gtsam/constrained/NonlinearConstraint.h
+++ b/gtsam/constrained/NonlinearConstraint.h
@@ -21,7 +21,7 @@
 #include <gtsam/inference/FactorGraph.h>
 #include <gtsam/inference/FactorGraph-inst.h>
 #include <gtsam/nonlinear/NonlinearFactor.h>
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
 #include <boost/serialization/base_object.hpp>
 #endif
 
@@ -77,7 +77,7 @@ class GTSAM_EXPORT NonlinearConstraint : public NoiseModelFactor {
   }
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
diff --git a/gtsam/constrained/NonlinearEqualityConstraint.h b/gtsam/constrained/NonlinearEqualityConstraint.h
index 017ca1607..f8b0205a1 100644
--- a/gtsam/constrained/NonlinearEqualityConstraint.h
+++ b/gtsam/constrained/NonlinearEqualityConstraint.h
@@ -39,7 +39,7 @@ class GTSAM_EXPORT NonlinearEqualityConstraint : public NonlinearConstraint {
   virtual ~NonlinearEqualityConstraint() {}
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
@@ -85,7 +85,7 @@ class ExpressionEqualityConstraint : public NonlinearEqualityConstraint {
   }
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
@@ -131,7 +131,7 @@ class GTSAM_EXPORT ZeroCostConstraint : public NonlinearEqualityConstraint {
   }
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
@@ -166,7 +166,7 @@ class GTSAM_EXPORT NonlinearEqualityConstraints : public FactorGraph<NonlinearEq
   NonlinearFactorGraph penaltyGraph(const double mu = 1.0) const;
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
diff --git a/gtsam/constrained/NonlinearInequalityConstraint.h b/gtsam/constrained/NonlinearInequalityConstraint.h
index 9dbf1f008..edc2b90e9 100644
--- a/gtsam/constrained/NonlinearInequalityConstraint.h
+++ b/gtsam/constrained/NonlinearInequalityConstraint.h
@@ -61,7 +61,7 @@ class GTSAM_EXPORT NonlinearInequalityConstraint : public NonlinearConstraint {
   virtual NoiseModelFactor::shared_ptr penaltyFactorEquality(const double mu = 1.0) const;
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
@@ -129,7 +129,7 @@ class GTSAM_EXPORT ScalarExpressionInequalityConstraint : public NonlinearInequa
   }
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>
@@ -169,7 +169,7 @@ class GTSAM_EXPORT NonlinearInequalityConstraints
                                           const double mu = 1.0) const;
 
  private:
-#ifdef GTSAM_ENABLE_BOOST_SERIALIZATION
+#if GTSAM_ENABLE_BOOST_SERIALIZATION
   /** Serialization function */
   friend class boost::serialization::access;
   template <class ARCHIVE>