diff --git a/composer.json b/composer.json
index d4c0f01..97d2133 100644
--- a/composer.json
+++ b/composer.json
@@ -40,7 +40,7 @@
 	"extra": {
 		"display-name": "phpBB Ideas",
 		"soft-require": {
-			"phpbb/phpbb": ">=3.3.0"
+			"phpbb/phpbb": ">=3.3.0,<4.0.0@dev"
 		}
 	}
 }
diff --git a/ext.php b/ext.php
index 82c3561..f9046e2 100644
--- a/ext.php
+++ b/ext.php
@@ -67,7 +67,7 @@ public static function status_name($id)
 	 */
 	public function is_enableable()
 	{
-		if (PHP_VERSION_ID < 70100 || phpbb_version_compare(PHPBB_VERSION, '3.3.0', '<'))
+		if (PHP_VERSION_ID < 70100 || phpbb_version_compare(PHPBB_VERSION, '3.3.0', '<') || phpbb_version_compare(PHPBB_VERSION, '4.0.0-dev', '>='))
 		{
 			return false;
 		}