diff --git a/RSP_Requirements_Design_Document/index.html b/RSP_Requirements_Design_Document/index.html
index 5c80f33..8995bb3 100644
--- a/RSP_Requirements_Design_Document/index.html
+++ b/RSP_Requirements_Design_Document/index.html
@@ -270,7 +270,7 @@ <h4>Abstract Model</h4>
                 <a href="http://www.w3.org/TR/2014/REC-rdf11-concepts-20140225/#section-IRIs">IRI</a>.</li>
             <li>RDF streams may have timestamps based on different notions of time (time instants, intervals) with 
               different semantics (application, validity, transactional).</li> 
-              In case no timestamp is associated to an RDF stream data element, the system is responsible of managing 
+              In case no timestamp is associated to an RDF stream data element, the system is responsible for managing the
               time-based ordering of stream elements.</li>
             <li>The RDF stream model should be susceptible to be restricted in order to facilitate implementation 
               and support efficient representation.</li>