diff --git a/argenta/app/entity.py b/argenta/app/entity.py
index 94014e3..6cb9da2 100644
--- a/argenta/app/entity.py
+++ b/argenta/app/entity.py
@@ -149,9 +149,9 @@ class App:
             self._unknown_command_handler = handler
 
 
-    def set_empty_command_handler(self, handler: Callable[[str], None]) -> None:
+    def set_empty_command_handler(self, handler: Callable[[], None]) -> None:
         args = getfullargspec(handler).args
-        if len(args) != 1:
+        if len(args) != 0:
             raise IncorrectNumberOfHandlerArgsException()
         else:
             self._empty_input_command_handler = handler
diff --git a/tests/system_tests/test_system_handling_non_standard_behavior.py b/tests/system_tests/test_system_handling_non_standard_behavior.py
index 162a407..ff13599 100644
--- a/tests/system_tests/test_system_handling_non_standard_behavior.py
+++ b/tests/system_tests/test_system_handling_non_standard_behavior.py
@@ -24,6 +24,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_unknown_command_handler(lambda command: print(f'Unknown command: {command.get_trigger()}'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -42,6 +43,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App(ignore_command_register=False)
         app.include_router(router)
+        app.set_unknown_command_handler(lambda command: print(f'Unknown command: {command.get_trigger()}'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -115,6 +117,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_unknown_command_handler(lambda command: print(f'Unknown command: {command.get_trigger()}'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -137,6 +140,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_unknown_command_handler(lambda command: print(f'Unknown command: {command.get_trigger()}'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -155,6 +159,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_invalid_input_flags_handler(lambda command: print(f'Incorrect flag syntax: "{command}"'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -173,6 +178,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_empty_command_handler(lambda: print('Empty input command'))
         app.start_polling()
 
         output = mock_stdout.getvalue()
@@ -191,6 +197,7 @@ class TestSystemHandlerNormalWork(unittest.TestCase):
 
         app = App()
         app.include_router(router)
+        app.set_repeated_input_flags_handler(lambda command: print(f'Repeated input flags: "{command}"'))
         app.start_polling()
 
         output = mock_stdout.getvalue()