diff --git a/molecule/core.py b/molecule/core.py
index <HASH>..<HASH> 100644
--- a/molecule/core.py
+++ b/molecule/core.py
@@ -189,7 +189,7 @@ class Molecule(object):
         :return: None
         """
 
-        inventory = ''
+        inventory = '[all]\n'
         for instance in self.driver.instances:
             inventory += self.driver.inventory_entry(instance)
Added ungrouped hosts under all (#<I>)

This works around an Ansible <I> bug [1].



[1] <URL>