diff --git a/composer.json b/composer.json
index 72d7fc5..93669be 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
 	"extra": {
 		"display-name": "Team Security Measures",
 		"soft-require": {
-			"phpbb/phpbb": ">=3.2.0"
+			"phpbb/phpbb": ">=3.2.0,<4.0.0@dev"
 		}
 	}
 }
diff --git a/ext.php b/ext.php
index 10bf98a..3db8454 100644
--- a/ext.php
+++ b/ext.php
@@ -27,7 +27,7 @@ class ext extends \phpbb\extension\base
 	 */
 	public function is_enableable()
 	{
-		return phpbb_version_compare(PHPBB_VERSION, '3.2.0', '>=');
+		return phpbb_version_compare(PHPBB_VERSION, '3.2.0', '>=') && phpbb_version_compare(PHPBB_VERSION, '4.0.0-dev', '<');
 	}
 
 	/**