diff --git a/language/oop5/traits.xml b/language/oop5/traits.xml
index 2d4b587974..4f9399358d 100644
--- a/language/oop5/traits.xml
+++ b/language/oop5/traits.xml
@@ -334,6 +334,12 @@ Hello World!
     Traits support the use of abstract methods in order to impose requirements
     upon the exhibiting class.
    </para>
+   <caution>
+    <simpara>
+     A concrete class fullfills this requirement by defining a concrete method
+     with the same name; its signature may be different.
+    </simpara>
+   </caution>
    <example xml:id="language.oop5.traits.abstract.ex1">
     <title>Express Requirements by Abstract Methods</title>
     <programlisting role="php">