diff --git a/nain4/src/n4_run_manager.hh b/nain4/src/n4_run_manager.hh
index 0f161b74..7d99e726 100644
--- a/nain4/src/n4_run_manager.hh
+++ b/nain4/src/n4_run_manager.hh
@@ -149,6 +149,8 @@ private:
     set_physics& apply_command    (const G4String& command ) { ui.apply    (command ); return *this; }
     set_physics& apply_early_macro(const G4String& filename) { ui.run_macro(filename); return *this; }
     set_physics& apply_cli_early_macro(                    ) { ui.run_early_macro()  ; return *this; }
+    set_physics& macro_path       (const G4String& path    ) { ui.prepend_path(path) ; return *this; }
+
     using fn_type = std::function<G4VUserPhysicsList* ()>;
     NEXT_STATE_BASIC(set_geometry, physics, G4VUserPhysicsList)
     NEXT_CONSTRUCT  (set_geometry, physics)
diff --git a/nain4/src/n4_ui.cc b/nain4/src/n4_ui.cc
index 7664cf0e..431afb4b 100644
--- a/nain4/src/n4_ui.cc
+++ b/nain4/src/n4_ui.cc
@@ -23,17 +23,20 @@ unsigned parse_beam_on(const std::string&  arg) {
 
 argparse::ArgumentParser define_args(const std::string& program_name, int argc, char** argv) {
   argparse::ArgumentParser args{program_name};
-  args.add_argument("--beam-on"    , "-n", "-b").metavar("N-EVENTS").help("run simulation with given number of events");
-  args.add_argument("--early-macro", "-e"      ).metavar("FILENAME").help("execute before run manager instantiation");
-  args.add_argument( "--late-macro", "-l"      ).metavar("FILENAME").help("execute after  run manager instantiation");
-  args.add_argument(  "--vis-macro", "-g"      ).metavar("FILENAME").help("switch from batch mode to GUI, executing this macro");
+  args.add_argument("--beam-on"    , "-n", "-b").metavar("N-EVENTS"   ).help("run simulation with given number of events");
+  args.add_argument("--early-macro", "-e"      ).metavar("FILENAME"   ).help("execute before run manager instantiation");
+  args.add_argument( "--late-macro", "-l"      ).metavar("FILENAME"   ).help("execute after  run manager instantiation");
+  args.add_argument(  "--vis-macro", "-g"      ).metavar("FILENAME"   ).help("switch from batch mode to GUI, executing this macro");
+  args.add_argument("--macro-path",  "-m"      ).metavar("MACRO-PATHS").help("Add directories to Geant4 macro search path")
+    .nargs(argparse::nargs_pattern::at_least_one)
+    .append();
 
   try {
     args.parse_args(argc, argv);
   } catch(const std::runtime_error& err) {
     std::cerr << err.what() << std::endl;
     std::cerr << args;
-    std::exit(EXIT_FAILURE);
+    throw err;
   }
 
   return args;
@@ -60,6 +63,13 @@ ui::ui(const std::string& program_name, int argc, char** argv, bool warn_empty_r
   late_macro  = args.present( "--late-macro");
   vis_macro   = args.present(  "--vis-macro");
 
+  // Here we use std::string because G4String does not work
+  auto macro_paths = args.get<std::vector<std::string>>("--macro-path");
+  for (auto& path : macro_paths) {
+    prepend_path(path);
+  }
+  g4_ui.ParseMacroSearchPath();
+
   if (warn_empty_run && ! (n_events.has_value() ^ vis_macro.has_value())) {
     std::cerr << "'" + program_name + "' is not going to do anything interesting without some command-line arguments.\n\n";
     std::cerr << args << std::endl;
diff --git a/nain4/src/n4_ui.hh b/nain4/src/n4_ui.hh
index bd9f726d..13ea3184 100644
--- a/nain4/src/n4_ui.hh
+++ b/nain4/src/n4_ui.hh
@@ -23,6 +23,9 @@ public:
   void  run_late_macro() { if ( late_macro.has_value()) { run_macro( late_macro.value()); }          }
   void   run_vis_macro() { if (  vis_macro.has_value()) { run_macro(  vis_macro.value()); }          }
 
+  void     set_path(G4String const& path) {                       g4_ui.SetMacroSearchPath(path) ;}
+  void prepend_path(G4String const& path) { set_path(path + ":" + g4_ui.GetMacroSearchPath(    ));}
+
 private:
   argparse::ArgumentParser args;
 
diff --git a/nain4/test/test-run-manager.cc b/nain4/test/test-run-manager.cc
index 5cc0d9f3..8501265a 100644
--- a/nain4/test/test-run-manager.cc
+++ b/nain4/test/test-run-manager.cc
@@ -22,6 +22,8 @@
 #include <catch2/catch_approx.hpp>
 #include <catch2/generators/catch_generators.hpp>
 #include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_contains.hpp>
+#include <stdexcept>
 
 using Catch::Approx;
 
@@ -153,3 +155,53 @@ TEST_CASE("nain run_manager exactly_one_world_volumes", "[nain][run_manager]") {
      .actions(do_nothing)
      .run();
 }
+
+TEST_CASE("test macropath with values", "[nain][run_manager][macropath]") {
+  auto hush = n4::silence{std::cout};
+
+  char *argv[] = { (char*)"progname-aaa"
+                 , (char*)"--macro-path"
+                 , (char*)"path-aaa"
+                 , (char*)"--macro-path"
+                 , (char*)"path-bbb"
+                 , (char*)"path-ccc"
+                 , NULL
+                 };
+
+  auto rm = n4::run_manager::create().ui("progname", 6, argv, false);
+
+  auto search_path = G4UImanager::GetUIpointer() -> GetMacroSearchPath();
+  std::cerr << search_path << std::endl;
+
+  CHECK(search_path.find("path-aaa") != std::string::npos);
+  CHECK(search_path.find("path-bbb") != std::string::npos);
+  CHECK(search_path.find("path-ccc") != std::string::npos);
+}
+
+
+TEST_CASE("test without macropath", "[nain][run_manager][macropath]") {
+  auto hush = n4::silence{std::cout};
+
+  char *argv[] = {(char*)"progname-aaa", NULL};
+
+  auto rm = n4::run_manager::create().ui("progname", 1, argv, false);
+
+  auto search_path = G4UImanager::GetUIpointer() -> GetMacroSearchPath();
+  std::cerr << "XXX" << search_path << "XXX" << std::endl;
+
+  CHECK(search_path == "");
+}
+
+
+TEST_CASE("test macropath without value", "[nain][run_manager][macropath]") {
+  auto hush = n4::silence{std::cout};
+
+  char *argv[] = {(char*)"progname-aaa", (char*)"--macro-path", NULL};
+
+  using Catch::Matchers::Contains;
+  // We tried
+  //   REQUIRE_THROWS_WITH( n4::run_manager::create().ui("progname", 2, argv, false)
+  //                      , Contains("Too few arguments") && Contains("--macro-path"));
+  // and variations on the there but nothing worked sensibly.
+  REQUIRE_THROWS_AS(n4::run_manager::create().ui("progname", 2, argv, false), std::runtime_error);
+}
diff --git a/templates/basic/flake/outputs.nix b/templates/basic/flake/outputs.nix
index f7b13d24..46830557 100644
--- a/templates/basic/flake/outputs.nix
+++ b/templates/basic/flake/outputs.nix
@@ -50,7 +50,8 @@
         export G4ABLADATA="${g4-data.G4ABLA}/share/Geant4-11.0.4/data/G4ABLA3.1"
         export G4INCLDATA="${g4-data.G4INCL}/share/Geant4-11.0.4/data/G4INCL1.0"
         export G4ENSDFSTATEDATA="${g4-data.G4ENSDFSTATE}/share/Geant4-11.0.4/data/G4ENSDFSTATE2.3"
-        exec CHANGEME-my-n4-prog "$@"
+
+        exec CHANGEME-my-n4-prog --macro-path ${self}/macs $*
       '';
     in { type = "app"; program = "${CHANGEME-wrap-my-package}/bin/CHANGEME-my-app"; };
 
diff --git a/templates/basic/src/n4app.cc b/templates/basic/src/n4app.cc
index 8c4021c7..e7caf399 100644
--- a/templates/basic/src/n4app.cc
+++ b/templates/basic/src/n4app.cc
@@ -119,9 +119,9 @@ int main(int argc, char* argv[]) {
   // ANCHOR: create_run_manager
   n4::run_manager::create()
     .ui("my-program-name", argc, argv)
-
+    .macro_path("macs")
     .apply_command("/my/straw_radius 0.5 m")
-    .apply_early_macro("macs/early-hard-wired.mac")
+    .apply_early_macro("early-hard-wired.mac")
     .apply_cli_early_macro() // CLI --early-macro executed at this point
     // .apply_command(...) // also possible after apply_early_macro
 
@@ -130,7 +130,7 @@ int main(int argc, char* argv[]) {
     .actions(create_actions(my, n_event))
 
     .apply_command("/my/particle e-")
-    .apply_late_macro("macs/late-hard-wired.mac")
+    .apply_late_macro("late-hard-wired.mac")
     .apply_cli_late_macro() // CLI --late-macro executed at this point
     // .apply_command(...) // also possible after apply_late_macro