diff --git a/test/common/spline/test_cubicspline.cc b/test/common/spline/test_cubicspline.cc
index a95ebb81cf8ddebbd2e84d8292adcd008cca63fe..e6fdb1094d4b2293f1e67880d35664ac493b4b26 100644
--- a/test/common/spline/test_cubicspline.cc
+++ b/test/common/spline/test_cubicspline.cc
@@ -85,6 +85,7 @@ int main(int argc, char** argv)
     const auto resultDerivPlot = eval([&](const double x) { return spline.evalDerivative(x); }, plotPoints);
 
     Dumux::GnuplotInterface<double> gnuplot(false);
+    gnuplot.setOpenPlotWindow(false);
     gnuplot.addDataSetToPlot(plotPoints, refPlot, "reference");
     gnuplot.addDataSetToPlot(plotPoints, refDerivPlot, "reference_derivative");
     gnuplot.addDataSetToPlot(plotPoints, resultPlot, "spline");
diff --git a/test/common/spline/test_monotonecubicspline.cc b/test/common/spline/test_monotonecubicspline.cc
index 4ff362388145eb75db28ae7a477208a619ff54b7..dc59b47701e148291e17191ae651697dbb261440 100644
--- a/test/common/spline/test_monotonecubicspline.cc
+++ b/test/common/spline/test_monotonecubicspline.cc
@@ -115,6 +115,7 @@ int main(int argc, char** argv)
     const auto resultDerivPlot = eval([&](const double x) { return spline.evalDerivative(x); }, plotPoints);
 
     Dumux::GnuplotInterface<double> gnuplot(/*persist=*/false);
+    gnuplot.setOpenPlotWindow(false);
     gnuplot.addDataSetToPlot(plotPoints, refPlot, "exp_reference");
     gnuplot.addDataSetToPlot(plotPoints, refDerivPlot, "exp_reference_derivative");
     gnuplot.addDataSetToPlot(plotPoints, resultPlot, "monotspline");