diff --git a/poky/bitbake/lib/bb/cache.py b/poky/bitbake/lib/bb/cache.py
index b309775..10910a6 100644
--- a/poky/bitbake/lib/bb/cache.py
+++ b/poky/bitbake/lib/bb/cache.py
@@ -216,7 +216,7 @@
 
         # Collect files we may need for possible world-dep
         # calculations
-        if not self.not_world:
+        if not bb.utils.to_boolean(self.not_world):
             cachedata.possible_world.append(fn)
         #else:
         #    logger.debug2("EXCLUDE FROM WORLD: %s", fn)