diff --git a/src/fr/devinsy/xidyn/presenters/URLPresenter.java b/src/fr/devinsy/xidyn/presenters/URLPresenter.java
index 7e3325e..e37ae31 100644
--- a/src/fr/devinsy/xidyn/presenters/URLPresenter.java
+++ b/src/fr/devinsy/xidyn/presenters/URLPresenter.java
@@ -74,8 +74,7 @@ public class URLPresenter extends StringPresenter
 		{
 			String errorMessage = "source not defined";
 			logger.error(errorMessage);
-			result = null;
-			throw new Exception(errorMessage);
+			throw new NullPointerException(errorMessage);
 		}
 		else
 		{