diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
index 227e9b93f3..2cd22e1a12 100644
--- a/UPGRADE-4.0.md
+++ b/UPGRADE-4.0.md
@@ -171,7 +171,9 @@ Serializer
    class has been removed. You should use the `CacheClassMetadataFactory` class
    instead.
    
- * Not defining the 6th argument `$format = null` of the `AbstractNormalizer::instantiateObject()` method when overriding it is not supported anymore.
+ * Not defining the 6th argument `$format = null` of the
+   `AbstractNormalizer::instantiateObject()` method when overriding it is not
+   supported anymore.
 
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