Incrementing the iterator would be a good idea
diff --git a/qt4/src/poppler-annotation.cc b/qt4/src/poppler-annotation.cc
index 14522b2..9d171a6 100644
--- a/qt4/src/poppler-annotation.cc
+++ b/qt4/src/poppler-annotation.cc
@@ -785,6 +785,7 @@
             lineElement.appendChild( pElement );
             pElement.setAttribute( "x", p.x() );
             pElement.setAttribute( "y", p.y() );
+            ++it;
         }
     }
 }