diff --git a/sphinx/ext/autosummary/__init__.py b/sphinx/ext/autosummary/__init__.py
index b1db7863f..00e4307eb 100644
--- a/sphinx/ext/autosummary/__init__.py
+++ b/sphinx/ext/autosummary/__init__.py
@@ -259,8 +259,8 @@ class Autosummary(Directive):
         table = nodes.table('')
         group = nodes.tgroup('', cols=2)
         table.append(group)
-        group.append(nodes.colspec('', colwidth=30))
-        group.append(nodes.colspec('', colwidth=70))
+        group.append(nodes.colspec('', colwidth=10))
+        group.append(nodes.colspec('', colwidth=90))
         body = nodes.tbody('')
         group.append(body)
 
@@ -319,7 +319,8 @@ def mangle_signature(sig, max_chars=30):
     else:
         sig = ", ".join(args)
 
-    return "(%s)" % sig
+    sig = unicode(sig).replace(u" ", u"\u00a0")
+    return u"(%s)" % sig
 
 # -- Importing items -----------------------------------------------------------
 
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index 37281fa9f..a0ea19614 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -30,6 +30,7 @@ from sphinx.util.smartypants import educateQuotesLatex
 HEADER = r'''%% Generated by Sphinx.
 \documentclass[%(papersize)s,%(pointsize)s%(classoptions)s]{%(docclass)s}
 %(inputenc)s
+%(utf8extra)s
 %(fontenc)s
 %(babel)s
 %(fontpkg)s
@@ -136,6 +137,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
         'pointsize':       '10pt',
         'classoptions':    '',
         'inputenc':        '\\usepackage[utf8]{inputenc}',
+        'utf8extra':       '\\DeclareUnicodeCharacter{00A0}{\nobreakspace}',
         'fontenc':         '\\usepackage[T1]{fontenc}',
         'babel':           '\\usepackage{babel}',
         'fontpkg':         '\\usepackage{times}',