diff --git a/sphinx/directives/desc.py b/sphinx/directives/desc.py
index 68706acf8..3c0bad157 100644
--- a/sphinx/directives/desc.py
+++ b/sphinx/directives/desc.py
@@ -319,7 +319,7 @@ def parse_c_type(node, ctype):
     # add cross-ref nodes for all words
     for part in filter(None, wsplit_re.split(ctype)):
         tnode = nodes.Text(part, part)
-        if part[0] in string.letters+'_' and part not in stopwords:
+        if part[0] in string.ascii_letters+'_' and part not in stopwords:
             pnode = addnodes.pending_xref(
                 '', reftype='ctype', reftarget=part, modname=None, classname=None)
             pnode += tnode
diff --git a/sphinx/environment.py b/sphinx/environment.py
index 826fe8faa..795e4594d 100644
--- a/sphinx/environment.py
+++ b/sphinx/environment.py
@@ -19,7 +19,7 @@ import difflib
 import cPickle as pickle
 from os import path
 from glob import glob
-from string import uppercase
+from string import ascii_uppercase as uppercase
 from itertools import izip, groupby
 try:
     import hashlib