diff --git a/src/elasticity/solvers/ElasticityNewmark.cpp b/src/elasticity/solvers/ElasticityNewmark.cpp
index d5db741571561a7d65822f9a8922a9d9c7f295f6..94d02c2ea51d2972f4bdcaccc97bab5474e92a09 100644
--- a/src/elasticity/solvers/ElasticityNewmark.cpp
+++ b/src/elasticity/solvers/ElasticityNewmark.cpp
@@ -124,8 +124,8 @@ void NewmarkSolver::updateOldValues(double dt, const Vector &u) {
 void NewmarkSolver::PlotIteration(double time) const {
   auto &plot_vel = mpp::plot("Velocity");
   plot_vel.AddData("Velocity", oldValues.Velocity());
-  plot_vel.PlotFile("Velocity" + to_string(time));
+  plot_vel.PlotFile("Velocity" + std::to_string(time));
   auto &plot_acc = mpp::plot("Acceleration");
   plot_acc.AddData("Acceleration", oldValues.Acceleration());
-  plot_acc.PlotFile("Acceleration" + to_string(time));
+  plot_acc.PlotFile("Acceleration" + std::to_string(time));
 }
\ No newline at end of file
diff --git a/test/elasticity/TestMainProgram.cpp b/test/elasticity/TestMainProgram.cpp
index 68de499ec3b5ef38b567c7f75b17001b46a12cb1..695987134e61a3f6b23fdd3f9c65077c97661e2e 100644
--- a/test/elasticity/TestMainProgram.cpp
+++ b/test/elasticity/TestMainProgram.cpp
@@ -26,18 +26,20 @@ protected:
     int level = mainProgram->initLevels[0];
     for (auto &sampleAmount : mainProgram->initSampleAmount) {
         for (int sample = 0; sample < sampleAmount; sample++) {
-            std::string permeability = "sample_" + to_string(level) +
-                "_" + to_string(sample) + "/permeability";
-            std::string u = "sample_" + to_string(level) +
-                "_" + to_string(sample) + "/u";
+            std::string permeability = "sample_" +  std::to_string(level) +
+                "_" +  std::to_string(sample) + "/permeability";
+            std::string u = "sample_" +  std::to_string(level) +
+                "_" +  std::to_string(sample) + "/u";
             ASSERT_TRUE(FileExists("data/vtk/" + permeability + ".vtk"));
             ASSERT_TRUE(FileExists("data/vtk/" + u + ".vtk"));
 
             if (level != mainProgram->initLevels[0]) {
-                std::string name_coarse = "sample_coarse_" + to_string(level) +
-                    "_" + to_string(sample) + "/permeability";
-                std::string u_coarse = "sample_coarse_" + to_string(level) +
-                    "_" + to_string(sample) + "/u";
+                std::string name_coarse = "sample_coarse_" +
+    std::to_string(level) +
+                    "_" +  std::to_string(sample) + "/permeability";
+                std::string u_coarse = "sample_coarse_" +  std::to_string(level)
+    +
+                    "_" +  std::to_string(sample) + "/u";
                 ASSERT_TRUE(FileExists("data/vtk/" + name_coarse + ".vtk"));
                 ASSERT_TRUE(FileExists("data/vtk/" + u_coarse + ".vtk"));
             }