diff --git a/gtsam/linear/NoiseModel.cpp b/gtsam/linear/NoiseModel.cpp
index 6ab26474a..f9a9ca804 100644
--- a/gtsam/linear/NoiseModel.cpp
+++ b/gtsam/linear/NoiseModel.cpp
@@ -20,6 +20,7 @@
 #include <gtsam/base/timing.h>
 
 #include <boost/foreach.hpp>
+#include <boost/format.hpp>
 #include <boost/random/linear_congruential.hpp>
 #include <boost/random/normal_distribution.hpp>
 #include <boost/random/variate_generator.hpp>
@@ -486,7 +487,7 @@ Isotropic::shared_ptr Isotropic::Variance(size_t dim, double variance, bool smar
 
 /* ************************************************************************* */
 void Isotropic::print(const string& name) const {
-  cout << name << "isotropic sigma " << " " << sigma_ << endl;
+  cout << boost::format("isotropic dim=%1% sigma=%2%") % dim() % sigma_ << endl;
 }
 
 /* ************************************************************************* */