diff --git a/lib/spack/spack/builder.py b/lib/spack/spack/builder.py
index 1ff2f777c0a..e201ba34691 100644
--- a/lib/spack/spack/builder.py
+++ b/lib/spack/spack/builder.py
@@ -121,6 +121,7 @@ def __init__(self, wrapped_pkg_object, root_builder):
                 new_cls_name,
                 bases,
                 {
+                    "__module__": package_cls.__module__,
                     "run_tests": property(lambda x: x.wrapped_package_object.run_tests),
                     "test_requires_compiler": property(
                         lambda x: x.wrapped_package_object.test_requires_compiler
@@ -129,7 +130,6 @@ def __init__(self, wrapped_pkg_object, root_builder):
                     "tester": property(lambda x: x.wrapped_package_object.tester),
                 },
             )
-            new_cls.__module__ = package_cls.__module__
             self.__class__ = new_cls
             self.__dict__.update(wrapped_pkg_object.__dict__)