diff --git a/pre_commit_hooks/requirements_txt_fixer.py b/pre_commit_hooks/requirements_txt_fixer.py
index 41e1ffc..ffabf2a 100644
--- a/pre_commit_hooks/requirements_txt_fixer.py
+++ b/pre_commit_hooks/requirements_txt_fixer.py
@@ -3,6 +3,10 @@
 import argparse
 
 
+PASS = 0
+FAIL = 1
+
+
 class Requirement(object):
 
     def __init__(self):
@@ -30,14 +34,14 @@
 
 def fix_requirements(f):
     requirements = []
-    before = list(f)
+    before = tuple(f)
     after = []
 
     before_string = b''.join(before)
 
     # If the file is empty (i.e. only whitespace/newlines) exit early
     if before_string.strip() == b'':
-        return 0
+        return PASS
 
     for line in before:
         # If the most recent requirement object has a value, then it's
@@ -60,19 +64,18 @@
             requirement.value = line
 
     for requirement in sorted(requirements):
-        for comment in requirement.comments:
-            after.append(comment)
+        after.extend(requirement.comments)
         after.append(requirement.value)
 
     after_string = b''.join(after)
 
     if before_string == after_string:
-        return 0
+        return PASS
     else:
         f.seek(0)
         f.write(after_string)
         f.truncate()
-        return 1
+        return FAIL
 
 
 def fix_requirements_txt(argv=None):
@@ -80,7 +83,7 @@
     parser.add_argument('filenames', nargs='*', help='Filenames to fix')
     args = parser.parse_args(argv)
 
-    retv = 0
+    retv = PASS
 
     for arg in args.filenames:
         with open(arg, 'rb+') as file_obj: