diff --git a/README.md b/README.md
index 7227c7f..83882ff 100644
--- a/README.md
+++ b/README.md
@@ -148,8 +148,8 @@ OPTIONS:
                               Separator character for CSV output
           --wdat, --write-to-dat TEXT
                               Path for writing results to DAT file
-          --wgnuplot, --write-to-gnuplot TEXT
-                              Path for writing results to Gnuplot file
+          --wgnuplot, --write-to-gnuplot Needs: --wdat
+                              Write results to Gnuplot file
           --ofmode, --output-file-mode CHAR:{a,o} [o]
                               Append or overwrite output file: 'a' for append, 'o' for
                               overwrite
@@ -198,7 +198,6 @@ Here's a list of examples of possible execution syntax:
     interval_b = 2
     tolerance = 1e-5
     max-iterations = 100
-    derivative = 2*x
     ```
 
 - CSV input file called input.csv with first row which is a header and "," separating different values, CSV output file called output.csv, Fixed Point Method to find the root of x^2-x, with initial guess 0.5, fixed point function x^2, and verbose output (given tolerance and maximum iterations)::
@@ -230,7 +229,7 @@ Here's a list of examples of possible execution syntax:
 - CLI input, DAT output file called output.dat, gnuplot writing method (a GNU Plot named output.png is created), Chords method to solve the equation x^3-8 starting from the two initial points 1 and 3:
 
     ```
-    root_cli --wgnuplot output cli --function x^3-8 chords --x0 1 --x1 3
+    root_cli --wdat output --wgnuplot cli --function x^3-8 chords --x0 1 --x1 3
     ```
 
 ## Typical program execution
diff --git a/ROOT/ROOT/main.cpp b/ROOT/ROOT/main.cpp
index 0584083..7a6c6b3 100644
--- a/ROOT/ROOT/main.cpp
+++ b/ROOT/ROOT/main.cpp
@@ -39,9 +39,9 @@ int main(int argc, char** argv) {
         ->capture_default_str();
 
     std::string write_to_dat;
-    app.add_option("--wdat,--write-to-dat", write_to_dat, "Path for writing results to DAT file");
-    std::string write_with_gnuplot;
-    app.add_option("--wgnuplot,--write-to-gnuplot", write_with_gnuplot, "Path for writing results to Gnuplot file");
+    auto* wdat = app.add_option("--wdat,--write-to-dat", write_to_dat, "Path for writing results to DAT file");
+    bool write_with_gnuplot = false;
+    app.add_flag("--wgnuplot,--write-to-gnuplot", write_with_gnuplot, "Write results to Gnuplot file")->needs(wdat);
 
     char append_or_overwrite = 'o';
     app.add_option("--ofmode,--output-file-mode", append_or_overwrite,
@@ -194,12 +194,14 @@ int main(int argc, char** argv) {
                                         append_or_overwrite == 'o');
         writer.write();
     } else if (!write_to_dat.empty()) {
-        Writer<Eigen::MatrixX2d> writer(results, WritingMethod::DAT, write_to_dat, ' ', append_or_overwrite == 'o');
-        writer.write();
-    } else if (!write_with_gnuplot.empty()) {
-        Writer<Eigen::MatrixX2d> writer(results, WritingMethod::GNUPLOT, write_with_gnuplot, ',',
-                                        append_or_overwrite == 'o');
-        writer.write();
+        if (write_with_gnuplot) {
+            Writer<Eigen::MatrixX2d> writer(results, WritingMethod::GNUPLOT, write_to_dat, ' ',
+                                            append_or_overwrite == 'o');
+            writer.write();
+        } else {
+            Writer<Eigen::MatrixX2d> writer(results, WritingMethod::DAT, write_to_dat, ' ', append_or_overwrite == 'o');
+            writer.write();
+        }
     }
 
     return 0;
diff --git a/ROOT/ROOT/writer.hpp b/ROOT/ROOT/writer.hpp
index 2052199..588f9e4 100644
--- a/ROOT/ROOT/writer.hpp
+++ b/ROOT/ROOT/writer.hpp
@@ -38,7 +38,7 @@ void Writer<Eigen::MatrixX2d>::write() {
     // LLM
     if (auto gp = dynamic_cast<PrinterGNUPlot<Eigen::Vector2d>*>(printer.get())) {
         gp->generate_gnuplot_script();
-        std::cout << "Gnuplot script generated: plot.plt\n";
+        std::cout << "Gnuplot script generated: " << this->filename << ".plt\n";
     }
 }
 
@@ -59,7 +59,8 @@ void Writer<T>::build_printer(std::unique_ptr<PrinterBase<V>>& printer) {
             printer = std::make_unique<PrinterGNUPlot<V>>(this->filename, this->overwrite);
             break;
         default:
-            throw std::runtime_error("Unknown writing method");
+            std::cerr << "\033[31mError: Unknown writing method.\033[0m\n";
+            std::exit(EXIT_FAILURE);
     }
 }
 
@@ -85,7 +86,8 @@ PrinterFile<V>::PrinterFile(const std::string& fname, bool ow_mode) {
     }
 
     if (!file.is_open()) {
-        throw std::runtime_error("File could not be opened");
+        std::cerr << "\033[31mError: could not open file " << this->filename << " for writing.\033[0m\n";
+        std::exit(EXIT_FAILURE);
     }
 }
 
diff --git a/ROOT/tests/integration/test_cli.cpp b/ROOT/tests/integration/test_cli.cpp
index 6588634..09e7a22 100644
--- a/ROOT/tests/integration/test_cli.cpp
+++ b/ROOT/tests/integration/test_cli.cpp
@@ -71,7 +71,8 @@ TEST(NewtonMethodWithReaderCSVWriterGNUPlot, QuadraticConvergesToMinus2) {
     std::string exe = "../../ROOT/root_cli";
 
     std::string cmd = exe +
-                      " --wgnuplot result"
+                      " --wdat result"
+                      " --wgnuplot"
                       " csv --file " +
                       filename;
 
@@ -131,7 +132,8 @@ TEST(NewtonMethodWithReaderDATWriterGNUPlot, QuadraticConvergesToMinus2) {
     std::string exe = "../../ROOT/root_cli";
 
     std::string cmd = exe +
-                      " --wgnuplot result"
+                      " --wdat result"
+                      " --wgnuplot"
                       " dat --file " +
                       filename;