diff --git a/src/wheel/__main__.py b/src/wheel/__main__.py
index 3c7de5fb..ce9a58d3 100644
--- a/src/wheel/__main__.py
+++ b/src/wheel/__main__.py
@@ -9,7 +9,7 @@
 
 
 def main() -> NoReturn:  # needed for console script
-    if __package__ == "":
+    if __spec__.parent == "":
         # To be able to run 'python wheel-0.9.whl/wheel':
         import os.path