diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index 393e3af9d12..370ccef593b 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -225,6 +225,9 @@ def source_id(self):
         """BundlePackages don't have a source id."""
         return ''
 
+    def mirror_id(self):
+        """BundlePackages don't have a mirror id."""
+
 
 @pattern.composite(interface=FetchStrategy)
 class FetchStrategyComposite(object):