diff --git a/gtsam/linear/MEstimators.cpp b/gtsam/linear/MEstimators.cpp
index 36fa939a6..2a8d6d99a 100644
--- a/gtsam/linear/MEstimators.cpp
+++ b/gtsam/linear/MEstimators.cpp
@@ -197,22 +197,22 @@ Tukey::shared_ptr Tukey::Create(double c, const ReweightScheme reweight) {
 }
 
 /* ************************************************************************* */
-// Welsh
+// Welsch
 /* ************************************************************************* */
-Welsh::Welsh(double c, const ReweightScheme reweight) : Base(reweight), c_(c), csquared_(c * c) {}
+Welsch::Welsch(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;
+void Welsch::print(const std::string &s="") const {
+  std::cout << s << ": Welsch (" << c_ << ")" << std::endl;
 }
 
-bool Welsh::equals(const Base &expected, double tol) const {
-  const Welsh* p = dynamic_cast<const Welsh*>(&expected);
+bool Welsch::equals(const Base &expected, double tol) const {
+  const Welsch* p = dynamic_cast<const Welsch*>(&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));
+Welsch::shared_ptr Welsch::Create(double c, const ReweightScheme reweight) {
+  return shared_ptr(new Welsch(c, reweight));
 }
 
 /* ************************************************************************* */
diff --git a/gtsam/linear/MEstimators.h b/gtsam/linear/MEstimators.h
index 77c8cee8e..59a39a94e 100644
--- a/gtsam/linear/MEstimators.h
+++ b/gtsam/linear/MEstimators.h
@@ -238,15 +238,15 @@ namespace gtsam {
         }
       };
 
-      /// Welsh implements the "Welsh" robust error model (Zhang97ivc)
-      class GTSAM_EXPORT Welsh : public Base {
+      /// Welsch implements the "Welsch" robust error model (Zhang97ivc)
+      class GTSAM_EXPORT Welsch : public Base {
       protected:
         double c_, csquared_;
 
       public:
-        typedef boost::shared_ptr<Welsh> shared_ptr;
+        typedef boost::shared_ptr<Welsch> shared_ptr;
 
-        Welsh(double c = 2.9846, const ReweightScheme reweight = Block);
+        Welsch(double c = 2.9846, const ReweightScheme reweight = Block);
         double sqrtWeight(double error) const {
           double xc2 = (error*error)/csquared_;
           return std::exp(-xc2/2.0);