diff --git a/docs/conf.py b/docs/conf.py
index 190473c..8836528 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -14,20 +14,14 @@
 import sphinx.environment
 from docutils.utils import get_source_line
 
-
-def _warn_node(self, msg, node):
-    """Do not warn on external images."""
-    if not msg.startswith('nonlocal image URI found:'):
-        self._warnfunc(msg, '{0}:{1}'.format(get_source_line(node)))
-
-sphinx.environment.BuildEnvironment.warn_node = _warn_node
-
-
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
 #needs_sphinx = '1.0'
 
+# Do not warn on external images.
+suppress_warnings = ['image.nonlocal_uri']
+
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
diff --git a/setup.py b/setup.py
index 8a5839a..53fb20b 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@
 
 extras_require = {
     'docs': [
-        "Sphinx>=1.3",
+        "Sphinx>=1.4.2",
     ],
     'jsonref': [
         'jsonref>=0.1',