diff --git a/.phpcs.xml b/.phpcs.xml
index d8870e5..eadd241 100644
--- a/.phpcs.xml
+++ b/.phpcs.xml
@@ -28,7 +28,7 @@
   <exclude-pattern>vendor/</exclude-pattern>
 
   <!-- The version set here matches the minimum version tested in CI. -->
-  <config name="minimum_supported_wp_version" value="6.6" />
+  <config name="minimum_supported_wp_version" value="6.0" />
 
   <!-- Define the prefixes that can be used by the plugin -->
   <rule ref="WordPress.NamingConventions.PrefixAllGlobals">
diff --git a/README.md b/README.md
index 4bf76d4..f6bbb87 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Tags: alleyinteractive, wp-video-sync
 
 Stable tag: 0.1.0
 
-Requires at least: 6.6
+Requires at least: 6.0
 
 Tested up to: 6.6
 
diff --git a/src/adapters/class-jw-player-7-for-wp.php b/src/adapters/class-jw-player-7-for-wp.php
index a3deea1..92db2bc 100644
--- a/src/adapters/class-jw-player-7-for-wp.php
+++ b/src/adapters/class-jw-player-7-for-wp.php
@@ -18,9 +18,9 @@ class JW_Player_7_For_WP implements Adapter {
 	/**
 	 * The date of the last modification to the last batch of videos.
 	 *
-	 * @var DateTimeImmutable
+	 * @var ?DateTimeImmutable
 	 */
-	private DateTimeImmutable $last_modified_date;
+	private ?DateTimeImmutable $last_modified_date;
 
 	/**
 	 * Fetches the date of the last modification to the last batch of videos.
diff --git a/src/class-sync-manager.php b/src/class-sync-manager.php
index c5e5a72..35ee1b8 100644
--- a/src/class-sync-manager.php
+++ b/src/class-sync-manager.php
@@ -28,9 +28,9 @@ class Sync_Manager {
 	/**
 	 * The adapter to use for fetching videos.
 	 *
-	 * @var Adapter
+	 * @var ?Adapter
 	 */
-	public Adapter $adapter;
+	public ?Adapter $adapter;
 
 	/**
 	 * A callback to run for each result when the sync runs.
@@ -75,6 +75,11 @@ public function maybe_schedule_sync(): void {
 	 * @throws Error If unable to parse the last sync as a DateTimeImmutable object.
 	 */
 	public function sync_videos(): void {
+		// If there isn't a valid adapter, bail.
+		if ( ! $this->adapter instanceof Adapter ) {
+			throw new Error( esc_html__( 'WP Video Sync: Unable to sync videos without a valid adapter.', 'wp-video-sync' ) );
+		}
+
 		// If there isn't a valid callback, bail.
 		if ( ! is_callable( $this->callback ) ) {
 			throw new Error( esc_html__( 'WP Video Sync: Unable to execute provided callback.', 'wp-video-sync' ) );