diff --git a/tools/DOI/doi.py b/tools/DOI/doi.py
index 523d8c6399e989ea5f51f3fd05bb997df28031fd..f27811292ed89caf678ee17b70bfcabae46b99a6 100644
--- a/tools/DOI/doi.py
+++ b/tools/DOI/doi.py
@@ -60,7 +60,6 @@ import xml.etree.ElementTree as ET
 
 import subprocess
 import re
-import os
 from datetime import date
 
 import authors
@@ -69,7 +68,7 @@ import authors
 # two forms:
 # - 'OK'
 # - 'OK ([DOI])'
-SUCCESS_RESPONSE = '^OK( \((.+)\))?$'
+SUCCESS_RESPONSE = r'^OK( \((.+)\))?$'
 
 # Point all "deleted" DOIs to here:
 INVALID_URL = 'http://www.datacite.org/invalidDOI'
@@ -210,8 +209,10 @@ def _http_request(body, method, url, options):
     ]
 
     # Set how loud cURL should be while running.
-    if options.debug: args.append('--verbose')
-    else: args.append('--silent')
+    if options.debug:
+        args.append('--verbose')
+    else:
+        args.append('--silent')
 
     args.append(url)
 
@@ -529,4 +530,4 @@ if __name__ == "__main__":
              'details.  Note that this does NOT delete the DOI.'
     )
 
-    run(parser.parse_args())
\ No newline at end of file
+    run(parser.parse_args())