diff --git a/lib/spack/docs/environments.rst b/lib/spack/docs/environments.rst
index 838dbf5f394..62ec2f74f76 100644
--- a/lib/spack/docs/environments.rst
+++ b/lib/spack/docs/environments.rst
@@ -545,8 +545,8 @@ environment and have a single view of it in the filesystem.
 
    The ``concretizer:unify`` config option was introduced in Spack 0.18 to
    replace the ``concretization`` property. For reference,
-   ``concretization: separately`` is replaced by ``concretizer:unify:true``,
-   and ``concretization: together`` is replaced by ``concretizer:unify:false``.
+   ``concretization: together`` is replaced by ``concretizer:unify:true``,
+   and ``concretization: separately`` is replaced by ``concretizer:unify:false``.
 
 .. admonition:: Re-concretization of user specs
 
@@ -1051,4 +1051,4 @@ the include is conditional.
    the ``--make-target-prefix`` flag and use the non-phony targets
    ``<target-prefix>/env`` and ``<target-prefix>/fetch`` as
    prerequisites, instead of the phony targets ``<target-prefix>/all``
-   and ``<target-prefix>/fetch-all`` respectively.
\ No newline at end of file
+   and ``<target-prefix>/fetch-all`` respectively.