diff --git a/core/modules/package_manager/config/schema/package_manager.schema.yml b/core/modules/package_manager/config/schema/package_manager.schema.yml
index 618bb4c26c66033311478a166ac2b14579026a73..89f888770ee1e2324dad2265ab618df273f9ff6a 100644
--- a/core/modules/package_manager/config/schema/package_manager.schema.yml
+++ b/core/modules/package_manager/config/schema/package_manager.schema.yml
@@ -4,7 +4,7 @@ package_name:
   constraints:
     Regex:
       # @see https://getcomposer.org/schema.json
-      pattern: '/^[a-z0-9]([_.-]?[a-z0-9]+)*/[a-z0-9](([_.]|-{1,2})?[a-z0-9]+)*$/'
+      pattern: '/^[a-z0-9]([_.-]?[a-z0-9]+)*\/[a-z0-9](([_.]|-{1,2})?[a-z0-9]+)*$/'
 
 package_manager.settings:
   type: config_object