diff --git a/sphinx/builders/epub.py b/sphinx/builders/epub.py
index 74c328ea7..a5f7a84d0 100644
--- a/sphinx/builders/epub.py
+++ b/sphinx/builders/epub.py
@@ -198,7 +198,7 @@ class EpubBuilder(StandaloneHTMLBuilder):
         """Collect section titles, their depth in the toc and the refuri."""
         # XXX: is there a better way than checking the attribute
         # toctree-l[1-8] on the parent node?
-        if isinstance(doctree, nodes.reference):
+        if isinstance(doctree, nodes.reference) and hasattr(doctree, 'refuri'):
             refuri = doctree['refuri']
             if refuri.startswith('http://') or refuri.startswith('https://') \
                 or refuri.startswith('irc:') or refuri.startswith('mailto:'):