1 files changed, 4 insertions, 1 deletions
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index f0a4e1c..880c493 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -922,9 +922,12 @@ def _sanity_check(name, package, level):
         raise TypeError('module name must be str, not {}'.format(type(name)))
     if level < 0:
         raise ValueError('level must be >= 0')
-    if package:
+    if level > 0:
         if not isinstance(package, str):
             raise TypeError('__package__ not set to a string')
+        elif not package:
+            raise ImportError('attempted relative import with no known parent '
+                              'package')
         elif package not in sys.modules:
             msg = ('Parent module {!r} not loaded, cannot perform relative '
                    'import')