diff --git a/sphinx/application.py b/sphinx/application.py
index c17cbb617..cee780c9c 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -29,7 +29,7 @@ from docutils.parsers.rst import convert_directive_function, \
 import sphinx
 from sphinx import package_dir, locale
 from sphinx.roles import XRefRole
-from sphinx.config import Config, convert_numfig_format
+from sphinx.config import Config
 from sphinx.errors import SphinxError, SphinxWarning, ExtensionError, \
     VersionRequirementError, ConfigError
 from sphinx.domains import ObjType
@@ -236,7 +236,6 @@ class Sphinx(object):
         self._init_i18n()
         # check all configuration values for permissible types
         self.config.check_types(self.warn)
-        self._post_init_config()
         # set up source_parsers
         self._init_source_parsers()
         # set up the build environment
@@ -271,9 +270,6 @@ class Sphinx(object):
             else:
                 self.info('not available for built-in messages')
 
-    def _post_init_config(self):
-        convert_numfig_format(self.config)
-
     def _init_source_parsers(self):
         for suffix, parser in iteritems(self._additional_source_parsers):
             if suffix not in self.config.source_suffix:
diff --git a/sphinx/config.py b/sphinx/config.py
index a5761e349..61516a1ff 100644
--- a/sphinx/config.py
+++ b/sphinx/config.py
@@ -289,12 +289,3 @@ class Config(object):
 
     def __contains__(self, name):
         return name in self.values
-
-
-def convert_numfig_format(config):
-    """ Convert numfi_format to new one. """
-
-    numfig_format = {}
-    for figtype, fmt in iteritems(config.numfig_format):
-        numfig_format[figtype] = fmt.replace('%s', '{number}')
-    config.numfig_format = numfig_format
diff --git a/sphinx/domains/std.py b/sphinx/domains/std.py
index f83afdab1..b7f2597d4 100644
--- a/sphinx/domains/std.py
+++ b/sphinx/domains/std.py
@@ -673,18 +673,20 @@ class StandardDomain(Domain):
             else:
                 title = env.config.numfig_format.get(figtype, '')
 
-            # convert old styled numfig_format to new style
-            title = title.replace('%s', '{number}')
-
-            if figname is None and '{name}' in title:
+            if figname is None and '%{name}' in title:
                 env.warn_node('the link has no caption: %s' % title, node)
                 return contnode
             else:
                 fignum = '.'.join(map(str, fignumber))
-                if figname:
-                    newtitle = title.format(name=figname, number=fignum)
+                if '{name}' in title or 'number' in title:
+                    # new style format (cf. "Fig.%{number}")
+                    if figname:
+                        newtitle = title.format(name=figname, number=fignum)
+                    else:
+                        newtitle = title.format(number=fignum)
                 else:
-                    newtitle = title.format(number=fignum)
+                    # old style format (cf. "Fig.%s")
+                    newtitle = title % fignum
         except KeyError as exc:
             env.warn_node('invalid numfig_format: %s (%r)' % (title, exc), node)
             return contnode
diff --git a/sphinx/util/texescape.py b/sphinx/util/texescape.py
index 861026b55..0a3192f6a 100644
--- a/sphinx/util/texescape.py
+++ b/sphinx/util/texescape.py
@@ -118,17 +118,10 @@ tex_replacements = [
     ('Ω', r'\(\Omega\)'),
     ('Ω', r'\(\Omega\)'),
 ]
-tex_pyformats = [
-    # map special chars of str.format() to escaped one
-    ('{', '{{'),
-    ('}', '}}'),
-]
-
 
 tex_escape_map = {}
 tex_replace_map = {}
 tex_hl_escape_map_new = {}
-tex_pyformat_map = {}
 
 
 def init():
@@ -140,6 +133,3 @@ def init():
         if a in '[]{}\\':
             continue
         tex_hl_escape_map_new[ord(a)] = b
-
-    for a, b in tex_pyformats:
-        tex_pyformat_map[ord(a)] = b
diff --git a/sphinx/writers/html.py b/sphinx/writers/html.py
index 7dd286cf7..ba2b758d8 100644
--- a/sphinx/writers/html.py
+++ b/sphinx/writers/html.py
@@ -291,7 +291,7 @@ class HTMLTranslator(BaseTranslator):
                     self.builder.warn(msg)
                 else:
                     numbers = self.builder.fignumbers[key][figure_id]
-                    self.body.append(prefix.format(number='.'.join(map(str, numbers))) + ' ')
+                    self.body.append(prefix % '.'.join(map(str, numbers)) + ' ')
                     self.body.append('</span>')
 
         figtype = self.builder.env.domains['std'].get_figtype(node)
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index 0a158297b..ca0f1a7dd 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -29,7 +29,7 @@ from sphinx.util import split_into
 from sphinx.util.i18n import format_date
 from sphinx.util.nodes import clean_astext, traverse_parent
 from sphinx.util.template import LaTeXRenderer
-from sphinx.util.texescape import tex_escape_map, tex_replace_map, tex_pyformat_map
+from sphinx.util.texescape import tex_escape_map, tex_replace_map
 from sphinx.util.smartypants import educate_quotes_latex
 
 
@@ -610,7 +610,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
 
     def generate_numfig_format(self, builder):
         ret = []
-        figure = self.builder.config.numfig_format['figure'].split('{number}', 1)
+        figure = self.builder.config.numfig_format['figure'].split('%s', 1)
         if len(figure) == 1:
             ret.append('\\def\\fnum@figure{%s}\n' %
                        escape_abbr(text_type(figure[0]).translate(tex_escape_map)))
@@ -623,7 +623,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
                            escape_abbr(text_type(figure[1]).translate(tex_escape_map)))
                 ret.append('\\makeatother\n')
 
-        table = self.builder.config.numfig_format['table'].split('{number}', 1)
+        table = self.builder.config.numfig_format['table'].split('%s', 1)
         if len(table) == 1:
             ret.append('\\def\\fnum@table{%s}\n' %
                        escape_abbr(text_type(table[0]).translate(tex_escape_map)))
@@ -636,7 +636,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
                            escape_abbr(text_type(table[1]).translate(tex_escape_map)))
                 ret.append('\\makeatother\n')
 
-        codeblock = self.builder.config.numfig_format['code-block'].split('{number}', 1)
+        codeblock = self.builder.config.numfig_format['code-block'].split('%s', 1)
         if len(codeblock) == 1:
             pass  # FIXME
         else:
@@ -1789,11 +1789,16 @@ class LaTeXTranslator(nodes.NodeVisitor):
         else:
             id = node.get('refuri', '')[1:].replace('#', ':')
 
-        title = node.get('title', '{number}').replace('%s', '{number}')
-        title = text_type(title).translate(tex_escape_map).translate(tex_pyformat_map)
-        title = title.replace('\\{{name\\}}', '{name}').replace('\\{{number\\}}', '{number}')
-        text = escape_abbr(title).format(name='\\nameref{%s}' % self.idescape(id),
-                                         number='\\ref{%s}' % self.idescape(id))
+        title = node.get('title', '%s')
+        title = text_type(title).translate(tex_escape_map).replace('\\%s', '%s')
+        if '\\{name\\}' in title or '\\{number\\}' in title:
+            # new style format (cf. "Fig.%{number}")
+            title = title.replace('\\{name\\}', '{name}').replace('\\{number\\}', '{number}')
+            text = escape_abbr(title).format(name='\\nameref{%s}' % self.idescape(id),
+                                             number='\\ref{%s}' % self.idescape(id))
+        else:
+            # old style format (cf. "Fig.%{number}")
+            text = escape_abbr(title) % ('\\ref{%s}' % self.idescape(id))
         hyperref = '\\hyperref[%s]{%s}' % (self.idescape(id), text)
         self.body.append(hyperref)
 
diff --git a/tests/roots/test-numfig/index.rst b/tests/roots/test-numfig/index.rst
index 499a1b7dc..939903839 100644
--- a/tests/roots/test-numfig/index.rst
+++ b/tests/roots/test-numfig/index.rst
@@ -53,5 +53,7 @@ test-tocdepth
 * Section.1 is :numref:`foo`
 * Section.2.1 is :numref:`bar_a`
 * Unnumbered section is :numref:`index`
+* Invalid numfig_format 01: :numref:`invalid <fig1>`
+* Invalid numfig_format 02: :numref:`Fig %s %s <fig1>`
 * Fig.1 is :numref:`Fig.{number} {name} <fig1>`
 * Section.1 is :numref:`Sect.{number} {name} <foo>`
diff --git a/tests/test_build_html.py b/tests/test_build_html.py
index 176590f75..d8aff88ab 100644
--- a/tests/test_build_html.py
+++ b/tests/test_build_html.py
@@ -506,6 +506,8 @@ def test_numfig_disabled(app, status, warning):
     warnings = warning.getvalue()
     assert 'index.rst:47: WARNING: numfig is disabled. :numref: is ignored.' in warnings
     assert 'index.rst:55: WARNING: no number is assigned for section: index' not in warnings
+    assert 'index.rst:56: WARNING: invalid numfig_format: invalid' not in warnings
+    assert 'index.rst:57: WARNING: invalid numfig_format: Fig %s %s' not in warnings
 
     expects = {
         'index.html': [
@@ -568,6 +570,8 @@ def test_numfig_without_numbered_toctree(app, status, warning):
     warnings = warning.getvalue()
     assert 'index.rst:47: WARNING: numfig is disabled. :numref: is ignored.' not in warnings
     assert 'index.rst:55: WARNING: no number is assigned for section: index' in warnings
+    assert 'index.rst:56: WARNING: invalid numfig_format: invalid' in warnings
+    assert 'index.rst:57: WARNING: invalid numfig_format: Fig %s %s' in warnings
 
     expects = {
         'index.html': [
@@ -666,6 +670,8 @@ def test_numfig_with_numbered_toctree(app, status, warning):
     warnings = warning.getvalue()
     assert 'index.rst:47: WARNING: numfig is disabled. :numref: is ignored.' not in warnings
     assert 'index.rst:55: WARNING: no number is assigned for section: index' in warnings
+    assert 'index.rst:56: WARNING: invalid numfig_format: invalid' in warnings
+    assert 'index.rst:57: WARNING: invalid numfig_format: Fig %s %s' in warnings
 
     expects = {
         'index.html': [
@@ -768,6 +774,8 @@ def test_numfig_with_prefix(app, status, warning):
     warnings = warning.getvalue()
     assert 'index.rst:47: WARNING: numfig is disabled. :numref: is ignored.' not in warnings
     assert 'index.rst:55: WARNING: no number is assigned for section: index' in warnings
+    assert 'index.rst:56: WARNING: invalid numfig_format: invalid' in warnings
+    assert 'index.rst:57: WARNING: invalid numfig_format: Fig %s %s' in warnings
 
     expects = {
         'index.html': [
@@ -866,6 +874,8 @@ def test_numfig_with_secnum_depth(app, status, warning):
     warnings = warning.getvalue()
     assert 'index.rst:47: WARNING: numfig is disabled. :numref: is ignored.' not in warnings
     assert 'index.rst:55: WARNING: no number is assigned for section: index' in warnings
+    assert 'index.rst:56: WARNING: invalid numfig_format: invalid' in warnings
+    assert 'index.rst:57: WARNING: invalid numfig_format: Fig %s %s' in warnings
 
     expects = {
         'index.html': [