diff --git a/lib/spack/spack/database.py b/lib/spack/spack/database.py
index 1adad5e90b7..f73d3765c8f 100644
--- a/lib/spack/spack/database.py
+++ b/lib/spack/spack/database.py
@@ -49,6 +49,7 @@
 from llnl.util.lock import *
 
 import spack.spec
+from spack.directory_layout import DirectoryLayoutError
 from spack.version import Version
 from spack.spec import *
 from spack.error import SpackError