diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 1d898d92aab66..41811f7fd0fff 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -129,14 +129,14 @@
 /packages/env                                   @noahtallen
 
 # PHP
-/lib                                            @timothybjacobs @spacedmonkey
-/lib/global-styles.php                          @timothybjabocs @spacedmonkey @oandregal
-/lib/theme.json                                 @timothybjabocs @spacedmonkey @oandregal
-/lib/theme-i18n.json                            @timothybjabocs @spacedmonkey @oandregal
-/lib/class-wp-theme-json-gutenberg.php          @timothybjabocs @spacedmonkey @oandregal
-/lib/class-wp-theme-json-resolver-gutenberg.php @timothybjabocs @spacedmonkey @oandregal
-/lib/full-site-editing                          @janw-me
-/phpunit/class-wp-theme-json-test.php           @oandregal
+/lib                                                                 @timothybjacobs @spacedmonkey
+/lib/global-styles.php                                               @timothybjabocs @spacedmonkey @oandregal
+/lib/compat/wordpress-5.9/theme.json                                                      @timothybjabocs @spacedmonkey @oandregal
+/lib/compat/wordpress-5.9/theme-i18n.json                                                 @timothybjabocs @spacedmonkey @oandregal
+/lib/compat/wordpress-5.9/class-wp-theme-json-gutenberg.php          @timothybjabocs @spacedmonkey @oandregal
+/lib/compat/wordpress-5.9/class-wp-theme-json-resolver-gutenberg.php @timothybjabocs @spacedmonkey @oandregal
+/lib/full-site-editing                                               @janw-me
+/phpunit/class-wp-theme-json-test.php                                @oandregal
 
 # Web App
 /packages/admin-manifest                        @ellatrix
diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/compat/wordpress-5.9/class-wp-theme-json-gutenberg.php
similarity index 100%
rename from lib/class-wp-theme-json-gutenberg.php
rename to lib/compat/wordpress-5.9/class-wp-theme-json-gutenberg.php
diff --git a/lib/class-wp-theme-json-resolver-gutenberg.php b/lib/compat/wordpress-5.9/class-wp-theme-json-resolver-gutenberg.php
similarity index 100%
rename from lib/class-wp-theme-json-resolver-gutenberg.php
rename to lib/compat/wordpress-5.9/class-wp-theme-json-resolver-gutenberg.php
diff --git a/lib/class-wp-theme-json-schema-gutenberg.php b/lib/compat/wordpress-5.9/class-wp-theme-json-schema-gutenberg.php
similarity index 100%
rename from lib/class-wp-theme-json-schema-gutenberg.php
rename to lib/compat/wordpress-5.9/class-wp-theme-json-schema-gutenberg.php
diff --git a/lib/theme-i18n.json b/lib/compat/wordpress-5.9/theme-i18n.json
similarity index 100%
rename from lib/theme-i18n.json
rename to lib/compat/wordpress-5.9/theme-i18n.json
diff --git a/lib/theme.json b/lib/compat/wordpress-5.9/theme.json
similarity index 100%
rename from lib/theme.json
rename to lib/compat/wordpress-5.9/theme.json
diff --git a/lib/load.php b/lib/load.php
index b34b9c1acbeb9..1262c56f0dd30 100644
--- a/lib/load.php
+++ b/lib/load.php
@@ -106,9 +106,9 @@ function gutenberg_is_experiment_enabled( $name ) {
 
 // These are used by some FSE features
 // as well as global styles.
-require __DIR__ . '/class-wp-theme-json-schema-gutenberg.php';
-require __DIR__ . '/class-wp-theme-json-gutenberg.php';
-require __DIR__ . '/class-wp-theme-json-resolver-gutenberg.php';
+require __DIR__ . '/compat/wordpress-5.9/class-wp-theme-json-schema-gutenberg.php';
+require __DIR__ . '/compat/wordpress-5.9/class-wp-theme-json-gutenberg.php';
+require __DIR__ . '/compat/wordpress-5.9/class-wp-theme-json-resolver-gutenberg.php';
 
 require __DIR__ . '/full-site-editing/full-site-editing.php';
 require __DIR__ . '/full-site-editing/block-templates.php';