diff --git a/sphinx/ext/autodoc/importer.py b/sphinx/ext/autodoc/importer.py
index db33b4215..857b6a91e 100644
--- a/sphinx/ext/autodoc/importer.py
+++ b/sphinx/ext/autodoc/importer.py
@@ -179,7 +179,7 @@ def import_object(modname, objpath, objtype='', attrgetter=safe_getattr, warning
             if isinstance(real_exc, SystemExit):
                 errmsg += ('; the module executes module level statement '
                            'and it might call sys.exit().')
-            elif isinstance(real_exc, ImportError):
+            elif isinstance(real_exc, ImportError) and real_exc.args:
                 errmsg += '; the following exception was raised:\n%s' % real_exc.args[0]
             else:
                 errmsg += '; the following exception was raised:\n%s' % traceback_msg