diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 2feea51fa57..d1479ec9de7 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -399,6 +399,7 @@ def version(self):
 
     @property
     def digests(self):
+        """All digests for the concretized package version."""
         versionInfo = self.versions[self.version]
         digests = {}
         if 'md5' in versionInfo: