diff --git a/README.md b/README.md
index 6f10340..76ed57a 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ python setup.py develop
 ## Usage
 
 ```bat
-turinglab <input_file> <input_string> <output_file>
+turinglab input_file output_dir [-t TESTS [TESTS ...]] [-e EMPTY_CHARACTER] [-f]
 ```
 
 ### Example
diff --git a/setup.py b/setup.py
index 61f39e7..c4b3fcb 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,6 @@ setup(
         'pydot',
         'requests',
         'sortedcontainers'
-    ],
     entry_points={
         'console_scripts': [
             'turinglab = turinglab.__main__:main'
diff --git a/turinglab/__main__.py b/turinglab/__main__.py
index 414ac15..dc9a4a7 100644
--- a/turinglab/__main__.py
+++ b/turinglab/__main__.py
@@ -36,7 +36,9 @@ def main():
     tests = []
 
     for test in args.tests:
-        test = test.replace(args.empty_character, 'λ')
+
+        if args.empty_character:
+            test = test.replace(args.empty_character, 'λ')
 
         tm = Emulator(program, test)