diff --git a/lib/spack/spack/package_base.py b/lib/spack/spack/package_base.py
index 1a320a205fc..85546409fbf 100644
--- a/lib/spack/spack/package_base.py
+++ b/lib/spack/spack/package_base.py
@@ -175,7 +175,7 @@ def windows_establish_runtime_linkage(self):
 detectable_packages = collections.defaultdict(list)
 
 
-class DetectablePackageMeta:
+class DetectablePackageMeta(type):
     """Check if a package is detectable and add default implementations
     for the detection function.
     """