diff --git a/src/Platform/b_grid.cc b/src/Platform/b_grid.cc
index c54a21c..6e9796d 100644
--- a/src/Platform/b_grid.cc
+++ b/src/Platform/b_grid.cc
@@ -37,7 +37,20 @@ void manageArguments(argparse::ArgumentParser& program)
     program.add_argument("--continue").help("Continue computing from that dataset").default_value(platform::GridSearch::NO_CONTINUE());
     program.add_argument("--only").help("Used with continue to compute that dataset only").default_value(false).implicit_value(true);
     program.add_argument("--exclude").default_value("[]").help("Datasets to exclude in json format, e.g. [\"dataset1\", \"dataset2\"]");
-    program.add_argument("--nested").help("Do a double/nested cross validation with n folds").default_value(0).scan<'i', int>();
+    program.add_argument("--nested").help("Set the double/nested cross validation number of folds").default_value(5).scan<'i', int>().action([](const std::string& value) {
+        try {
+            auto k = stoi(value);
+            if (k < 2) {
+                throw std::runtime_error("Number of nested folds must be greater than 1");
+            }
+            return k;
+        }
+        catch (const runtime_error& err) {
+            throw std::runtime_error(err.what());
+        }
+        catch (...) {
+            throw std::runtime_error("Number of nested folds must be an integer");
+        }});
     program.add_argument("--score").help("Score used in gridsearch").default_value("accuracy");
     program.add_argument("-f", "--folds").help("Number of folds").default_value(stoi(env.get("n_folds"))).scan<'i', int>().action([](const std::string& value) {
         try {