Fix debug statement hook
diff --git a/pre_commit_hooks/debug_statement_hook.py b/pre_commit_hooks/debug_statement_hook.py
index 1335cb0..7e088ef 100644
--- a/pre_commit_hooks/debug_statement_hook.py
+++ b/pre_commit_hooks/debug_statement_hook.py
@@ -45,7 +45,7 @@
 
 def debug_statement_hook(argv):
     parser = argparse.ArgumentParser()
-    parser.add_argument('filenames', nargs='+', help='Filenames to run')
+    parser.add_argument('filenames', nargs='*', help='Filenames to run')
     args = parser.parse_args()
 
     retv = 0
diff --git a/tests/debug_statement_hook_test.py b/tests/debug_statement_hook_test.py
index ecfdbc0..5a6040b 100644
--- a/tests/debug_statement_hook_test.py
+++ b/tests/debug_statement_hook_test.py
@@ -2,8 +2,8 @@
 import ast
 import pytest
 
-from pre_commit_hooks.debug_statement_hook import ImportStatementParser, \
-    DebugStatement
+from pre_commit_hooks.debug_statement_hook import DebugStatement
+from pre_commit_hooks.debug_statement_hook import ImportStatementParser
 
 
 @pytest.fixture