diff --git a/pythainlp/cli/__init__.py b/pythainlp/cli/__init__.py
index e7001f5bb..83995f9a5 100644
--- a/pythainlp/cli/__init__.py
+++ b/pythainlp/cli/__init__.py
@@ -5,7 +5,7 @@
 
 import io
 import sys
-from argparse import ArgumentParser
+from argparse import ArgumentError, ArgumentParser
 
 sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding="utf-8")
 sys.stderr = io.TextIOWrapper(sys.stderr.buffer, encoding="utf-8")
@@ -23,6 +23,14 @@ def make_usage(command: str) -> dict:
 
 
 def exit_if_empty(command: str, parser: ArgumentParser) -> None:
+    """Print help and exit if command is empty.
+
+    :param command: command from command line
+    :type command: str
+    :param parser: parser object of the app
+    :type parser: ArgumentParser
+    """
     if not command:
-        parser.print_help()
-        sys.exit(0)
+        if parser:
+            parser.print_help()
+        raise ArgumentError(None, "No command provided.")
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 15b4750bb..eb68668ac 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -13,6 +13,10 @@
 
 
 class CliTestCase(unittest.TestCase):
+    def test_cli(self):
+        with self.assertRaises((ArgumentError, SystemExit)):
+            cli.exit_if_empty("", None)
+
     def test_cli_main(self):
         # call with no argument, should exit with 2
         with self.assertRaises(SystemExit) as ex:
@@ -20,12 +24,10 @@ def test_cli_main(self):
         self.assertEqual(ex.exception.code, 2)
 
         with self.assertRaises((ArgumentError, SystemExit)):
-            self.assertIsNone(__main__.main(["thainlp"]))
+            __main__.main(["thainlp"])
 
         with self.assertRaises((ArgumentError, SystemExit)):
-            self.assertIsNone(
-                __main__.main(["thainlp", "NOT_EXIST", "command"])
-            )
+            __main__.main(["thainlp", "NOT_EXIST", "command"])
 
         self.assertIsNone(__main__.main(["thainlp", "data", "path"]))