diff --git a/Examples/loadFMAAndRunFMM.cpp b/Examples/loadFMAAndRunFMM.cpp
index bc3eb820dab1394173f524908c014ed1a82b3904..cb6dc9aadb111d3d9bcb45f3c313a50db1c31c05 100644
--- a/Examples/loadFMAAndRunFMM.cpp
+++ b/Examples/loadFMAAndRunFMM.cpp
@@ -66,14 +66,11 @@ int main(int argc, char** argv)
 
     // GCC versions before 5.0 have not implemented move constructors to streams
     std::vector<std::unique_ptr<std::ofstream>> outfiles;
-    for ( int i = 0; i < args.treeHeight(); i++ ) {
+    for ( int zoneIdx = 0; zoneIdx < args.treeHeight(); zoneIdx++ ) {
         std::unique_ptr<std::ofstream> out(
             new std::ofstream( args.outFileName()
-                               + "_"
-                               + std::to_string(args.zoneCount())
-                               + "z"
-                               + "."
-                               + std::to_string(i)
+                               + "_" + std::to_string(args.zoneCount()) + "z" 
+                               + "." + std::to_string(zoneIdx)
                                + args.outFileExt()));
         *out << "x,y,z,zone" << std::endl;
         outfiles.push_back(std::move(out));
diff --git a/Examples/loadFMAAndRunFMMArgs.hpp b/Examples/loadFMAAndRunFMMArgs.hpp
index e55bdef43f0aef326485dc933e5ec7c435e056ff..2f12859453e2cfef347f7d5a9e3cbf865ac27f18 100644
--- a/Examples/loadFMAAndRunFMMArgs.hpp
+++ b/Examples/loadFMAAndRunFMMArgs.hpp
@@ -44,8 +44,9 @@ class loadFMAAndRunFMMArgs {
     TCLAP::ValueArg <std::string>
     _outFileExt { "x", "output-file-extension",
             "Output files extension. One file is created for each level in the"
-            " tree. Each file has a 'basename.$i.extension' extension where $i"
-            " is the level. Default value is " + _outFileNameExtInit + ".",
+            " tree. Each file has a 'basename_$nbZones$z.$i$.extension' "
+            "extension where $i is the level. Default value is "
+            + _outFileNameExtInit + ".",
             false, _outFileNameExtInit, "suffix", _cmd};
 
     TCLAP::ValueArg <std::string>