diff --git a/lib/spack/llnl/util/lock.py b/lib/spack/llnl/util/lock.py
index 179ed50158d..497f36696c7 100644
--- a/lib/spack/llnl/util/lock.py
+++ b/lib/spack/llnl/util/lock.py
@@ -139,7 +139,7 @@ def get_fh(self, path):
     def release_by_stat(self, stat):
         key = (stat.st_dev, stat.st_ino, os.getpid())
         open_file = self._descriptors.get(key)
-        assert open_file, "Attempted to close non-existing inode: %s" % stat.st_inode
+        assert open_file, "Attempted to close non-existing inode: %s" % stat.st_ino
 
         open_file.refs -= 1
         if not open_file.refs: