diff --git a/CHANGES b/CHANGES
index ae5389249..9481299cb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -20,6 +20,7 @@ Bugs fixed
 * #3205: sphinx.util.requests crashes with old pyOpenSSL (< 0.14)
 * #3220: KeyError when having a duplicate citation
 * #3200: LaTeX: xref inside desc_name not allowed
+* #3228: ``build_sphinx`` command crashes when missing dependency
 
 
 Release 1.5 (released Dec 5, 2016)
diff --git a/sphinx/setup_command.py b/sphinx/setup_command.py
index c23f22228..0c49b0e89 100644
--- a/sphinx/setup_command.py
+++ b/sphinx/setup_command.py
@@ -165,6 +165,7 @@ class BuildDoc(Command):
         if self.copyright:
             confoverrides['copyright'] = self.copyright
 
+        app = None
         try:
             with docutils_namespace():
                 app = Sphinx(self.source_dir, self.config_dir,