diff --git a/gtsam/nonlinear/NonlinearFactor.h b/gtsam/nonlinear/NonlinearFactor.h
index 85da5387a..010341804 100644
--- a/gtsam/nonlinear/NonlinearFactor.h
+++ b/gtsam/nonlinear/NonlinearFactor.h
@@ -40,6 +40,8 @@
 
 namespace gtsam {
 
+using boost::assign::cref_list_of;
+
 /* ************************************************************************* */
 /**
  * Nonlinear factor base class
@@ -366,7 +368,7 @@ public:
    *  @param key1 by which to look up X value in Values
    */
   NoiseModelFactor1(const SharedNoiseModel& noiseModel, Key key1) :
-    Base(noiseModel, boost::assign::cref_list_of<1>(key1)) {}
+    Base(noiseModel, cref_list_of<1>(key1)) {}
 
   /** Calls the 1-key specific version of evaluateError, which is pure virtual
    *  so must be implemented in the derived class.
@@ -435,7 +437,7 @@ public:
    * @param j2 key of the second variable
    */
   NoiseModelFactor2(const SharedNoiseModel& noiseModel, Key j1, Key j2) :
-    Base(noiseModel, boost::assign::cref_list_of<2>(j1)(j2)) {}
+    Base(noiseModel, cref_list_of<2>(j1)(j2)) {}
 
   virtual ~NoiseModelFactor2() {}
 
@@ -512,7 +514,7 @@ public:
    * @param j3 key of the third variable
    */
   NoiseModelFactor3(const SharedNoiseModel& noiseModel, Key j1, Key j2, Key j3) :
-    Base(noiseModel, boost::assign::cref_list_of<3>(j1)(j2)(j3)) {}
+    Base(noiseModel, cref_list_of<3>(j1)(j2)(j3)) {}
 
   virtual ~NoiseModelFactor3() {}
 
@@ -591,7 +593,7 @@ public:
    * @param j4 key of the fourth variable
    */
   NoiseModelFactor4(const SharedNoiseModel& noiseModel, Key j1, Key j2, Key j3, Key j4) :
-    Base(noiseModel, boost::assign::cref_list_of<4>(j1)(j2)(j3)(j4)) {}
+    Base(noiseModel, cref_list_of<4>(j1)(j2)(j3)(j4)) {}
 
   virtual ~NoiseModelFactor4() {}
 
@@ -674,7 +676,7 @@ public:
    * @param j5 key of the fifth variable
    */
   NoiseModelFactor5(const SharedNoiseModel& noiseModel, Key j1, Key j2, Key j3, Key j4, Key j5) :
-    Base(noiseModel, boost::assign::cref_list_of<5>(j1)(j2)(j3)(j4)(j5)) {}
+    Base(noiseModel, cref_list_of<5>(j1)(j2)(j3)(j4)(j5)) {}
 
   virtual ~NoiseModelFactor5() {}
 
@@ -761,7 +763,7 @@ public:
    * @param j6 key of the fifth variable
    */
   NoiseModelFactor6(const SharedNoiseModel& noiseModel, Key j1, Key j2, Key j3, Key j4, Key j5, Key j6) :
-    Base(noiseModel, boost::assign::cref_list_of<6>(j1)(j2)(j3)(j4)(j5)(j6)) {}
+    Base(noiseModel, cref_list_of<6>(j1)(j2)(j3)(j4)(j5)(j6)) {}
 
   virtual ~NoiseModelFactor6() {}