diff --git a/CategoryLockdown.php b/CategoryLockdown.php
index 1e17ec7..caa13c1 100644
--- a/CategoryLockdown.php
+++ b/CategoryLockdown.php
@@ -16,6 +16,8 @@ class CategoryLockdown {
 	 */
 	public static function onGetUserPermissionsErrors( $title, $user, $action, &$result ) {
 		global $wgCategoryLockdown;
+		global $wgCategoryGroupLockdown;
+		global $wgCategoryLockdownWhitelist;
 
 		$explicitGroups = MediaWikiServices::getInstance()->getUserGroupManager()->getUserGroups( $user );
 		$implicitGroups = MediaWikiServices::getInstance()->getUserGroupManager()->getUserImplicitGroups( $user );
@@ -26,6 +28,11 @@ class CategoryLockdown {
 			return;
 		}
 
+		// Rules doesn’t apply to the whitelist
+		if ( in_array( $title, $wgCategoryLockdownWhitelist ) ) {
+			return;
+		}
+
 		$categories = array_keys( $title->getParentCategories() );
 
 		// Apply rules to the category page itself
@@ -33,16 +40,11 @@ class CategoryLockdown {
 			$categories[] = $title->getFullText();
 		}
 
+		// Support "Category:Top_secret", "Category:Top secret", "Top_secret" and "Top secret"
+		$categories = array_map( fn($c) => str_replace( '_', ' ', substr( $c, strpos( $c, ':' ) + 1 ) ), $categories );
 		$combinedGroups = [];
 		foreach ( $categories as $category ) {
-			// Support "Category:Top_secret", "Category:Top secret", "Top_secret" and "Top secret"
-			$category = substr( $category, strpos( $category, ':' ) + 1 );
-			$category = str_replace( '_', ' ', $category );
 			$permissions = $wgCategoryLockdown[ $category ] ?? null;
-			if ( !$permissions ) {
-				$category = str_replace( ' ', '_', $category );
-				$permissions = $wgCategoryLockdown[ $category ] ?? null;
-			}
 			if ( !$permissions ) {
 				continue;
 			}
@@ -57,15 +59,40 @@ class CategoryLockdown {
 				$combinedGroups[] = $allowedGroup;
 			}
 		}
-		if ( $combinedGroups ) {
-			foreach ( $userGroups as $userGroup ) {
-				if ( in_array( $userGroup, $combinedGroups ) ) {
-					return;
-				}
+
+		$allow = false;
+		foreach ( $userGroups as $userGroup ) {
+			if ( in_array( $userGroup, $combinedGroups ) ) {
+				$allow = true;
+				break;
 			}
+		}
+		if ( $combinedGroups && !$allow ) {
 			$result = [ 'categorylockdown-error', implode( ', ', $combinedGroups ) ];
 			return false;
 		}
+
+		$allow = true;
+		foreach ( $wgCategoryGroupLockdown as $group => $groupCategories ) {
+			if ( str_starts_with( $group, "!") ?
+					    in_array( substr($group, 1), $userGroups ) :
+						!in_array( $group, $userGroups ) ) {
+				continue; # Skip if this group rule doesn’t match the user
+			}
+
+			$requiredCat = $groupCategories[$action] ?? [];
+			$groupLocked = true;
+			foreach ( $requiredCat as $c ) {
+				if ( in_array( $c, $categories ) ) {
+					$groupLocked = false;
+					break; # One of the category is present, we can grant this action.
+				}
+			}
+			if ( $groupLocked ) {
+				$result = [ 'categorylockdown-error', implode( ', ', $requiredCat ) ];
+				return false; # This group of users need a category from groupCategories on this page to perform $action
+			}
+		}
 	}
 
 	/**