diff --git a/lib/spack/spack/config.py b/lib/spack/spack/config.py
index 7ea89b7c98..8df9e514c3 100644
--- a/lib/spack/spack/config.py
+++ b/lib/spack/spack/config.py
@@ -536,7 +536,7 @@ def update_config(self, section, update_data, scope=None, force=False):
             msg = ('The "{0}" section of the configuration needs to be written'
                    ' to disk, but is currently using a deprecated format. '
                    'Please update it using:\n\n'
-                   '\tspack config [--scope=<scope] update {0}\n\n'
+                   '\tspack config [--scope=<scope>] update {0}\n\n'
                    'Note that previous versions of Spack will not be able to '
                    'use the updated configuration.')
             msg = msg.format(section)