diff --git a/gtsam.h b/gtsam.h
index 04575f84d..09b5b59e6 100644
--- a/gtsam.h
+++ b/gtsam.h
@@ -1422,8 +1422,8 @@ virtual class Welsch: gtsam::noiseModel::mEstimator::Base {
 };
 
 virtual class GemanMcClure: gtsam::noiseModel::mEstimator::Base {
-  GemanMcClure(double k);
-  static gtsam::noiseModel::mEstimator::GemanMcClure* Create(double k);
+  GemanMcClure(double c);
+  static gtsam::noiseModel::mEstimator::GemanMcClure* Create(double c);
 
   // enabling serialization functionality
   void serializable() const;
diff --git a/gtsam/linear/NoiseModel.cpp b/gtsam/linear/NoiseModel.cpp
index 68e579718..e0b7c8b17 100644
--- a/gtsam/linear/NoiseModel.cpp
+++ b/gtsam/linear/NoiseModel.cpp
@@ -731,6 +731,7 @@ Fair::Fair(double c, const ReweightScheme reweight) : Base(reweight), c_(c) {
 double Fair::weight(double error) const {
   return 1.0 / (1.0 + std::abs(error) / c_);
 }
+
 double Fair::residual(double error) const {
   const double absError = std::abs(error);
   const double normalizedError = absError / c_;
@@ -839,6 +840,7 @@ double Tukey::weight(double error) const {
   }
   return 0.0;
 }
+
 double Tukey::residual(double error) const {
   double absError = std::abs(error);
   if (absError <= c_) {
@@ -894,24 +896,6 @@ Welsch::shared_ptr Welsch::Create(double c, const ReweightScheme reweight) {
   return shared_ptr(new Welsch(c, reweight));
 }
 
-#ifdef GTSAM_ALLOW_DEPRECATED_SINCE_V4
-Welsh::Welsh(double c, const ReweightScheme reweight) : Base(reweight), c_(c), csquared_(c * c) {}
-
-void Welsh::print(const std::string &s="") const {
-  std::cout << s << ": Welsh (" << c_ << ")" << std::endl;
-}
-
-bool Welsh::equals(const Base &expected, double tol) const {
-  const Welsh* p = dynamic_cast<const Welsh*>(&expected);
-  if (p == NULL) return false;
-  return std::abs(c_ - p->c_) < tol;
-}
-
-Welsh::shared_ptr Welsh::Create(double c, const ReweightScheme reweight) {
-  return shared_ptr(new Welsh(c, reweight));
-}
-#endif
-
 /* ************************************************************************* */
 // GemanMcClure
 /* ************************************************************************* */
@@ -992,16 +976,13 @@ DCS::shared_ptr DCS::Create(double c, const ReweightScheme reweight) {
 // L2WithDeadZone
 /* ************************************************************************* */
 
-L2WithDeadZone::L2WithDeadZone(double k, const ReweightScheme reweight) : Base(reweight), k_(k) {
+L2WithDeadZone::L2WithDeadZone(double k, const ReweightScheme reweight)
+ : Base(reweight), k_(k) {
   if (k_ <= 0) {
     throw runtime_error("mEstimator L2WithDeadZone takes only positive double in constructor.");
   }
 }
 
-double L2WithDeadZone::residual(double error) const {
-  const double abs_error = std::abs(error);
-  return (abs_error < k_) ? 0.0 : 0.5*(k_-abs_error)*(k_-abs_error);
-}
 double L2WithDeadZone::weight(double error) const {
   // note that this code is slightly uglier than residual, because there are three distinct
   // cases to handle (left of deadzone, deadzone, right of deadzone) instead of the two
@@ -1011,6 +992,11 @@ double L2WithDeadZone::weight(double error) const {
   else return (k_+error)/error;
 }
 
+double L2WithDeadZone::residual(double error) const {
+  const double abs_error = std::abs(error);
+  return (abs_error < k_) ? 0.0 : 0.5*(k_-abs_error)*(k_-abs_error);
+}
+
 void L2WithDeadZone::print(const std::string &s="") const {
   std::cout << s << ": L2WithDeadZone (" << k_ << ")" << std::endl;
 }
diff --git a/gtsam/linear/NoiseModel.h b/gtsam/linear/NoiseModel.h
index d93a7f825..d6b0a7331 100644
--- a/gtsam/linear/NoiseModel.h
+++ b/gtsam/linear/NoiseModel.h
@@ -725,11 +725,11 @@ namespace gtsam {
         typedef boost::shared_ptr<Null> shared_ptr;
 
         Null(const ReweightScheme reweight = Block) : Base(reweight) {}
-        virtual ~Null() {}
-        virtual double weight(double /*error*/) const { return 1.0; }
-        virtual double residual(double error) const { return error; }
-        virtual void print(const std::string &s) const;
-        virtual bool equals(const Base& /*expected*/, double /*tol*/) const { return true; }
+        ~Null() {}
+        double weight(double /*error*/) const { return 1.0; }
+        double residual(double error) const { return error; }
+        void print(const std::string &s) const;
+        bool equals(const Base& /*expected*/, double /*tol*/) const { return true; }
         static shared_ptr Create() ;
 
       private:
@@ -951,9 +951,9 @@ namespace gtsam {
       public:
           typedef boost::shared_ptr<L2WithDeadZone> shared_ptr;
 
-          L2WithDeadZone(double k, const ReweightScheme reweight = Block);
-          double residual(double error) const override;
+          L2WithDeadZone(double k = 1.0, const ReweightScheme reweight = Block);
           double weight(double error) const override;
+          double residual(double error) const override;
           void print(const std::string &s) const;
           bool equals(const Base& expected, double tol=1e-8) const;
           static shared_ptr Create(double k, const ReweightScheme reweight = Block);