diff --git a/lib/spack/spack/package.py b/lib/spack/spack/package.py
index 38bc6fa3f41245d1c2a53d783b22f168de913cfd..fe19e5d400147e4ab5be440e7698c557c497dc31 100644
--- a/lib/spack/spack/package.py
+++ b/lib/spack/spack/package.py
@@ -722,7 +722,7 @@ def do_fetch(self, mirror_only=False):
 
             if not ignore_checksum:
                 raise FetchError("Will not fetch %s" %
-                                 self.spec.format('$_$@'), checksum_msg)
+                                 self.spec.format('$_$@'), ck_msg)
 
         self.stage.fetch(mirror_only)