diff --git a/lib/spack/spack/directives_meta.py b/lib/spack/spack/directives_meta.py
index caa69bb6bf3..a02d11d6d40 100644
--- a/lib/spack/spack/directives_meta.py
+++ b/lib/spack/spack/directives_meta.py
@@ -144,7 +144,6 @@ class Foo(Package):
         Package class, and it's how Spack gets information from the
         packages to the core.
         """
-        global directive_names
 
         if isinstance(dicts, str):
             dicts = (dicts,)