diff --git a/etemplate/js/et2_widget_gantt.js b/etemplate/js/et2_widget_gantt.js
index 778cf03c8f..f1a8dff4c1 100644
--- a/etemplate/js/et2_widget_gantt.js
+++ b/etemplate/js/et2_widget_gantt.js
@@ -753,4 +753,33 @@ $j(function() {
 			return "weekend"
 		}
 	};
+
+	// Link styling
+	gantt.templates.link_class = function(link) {
+		var link_class = '';
+		var source = gantt.getTask(link.source);
+		var target = gantt.getTask(link.target);
+		var valid = true;
+
+		var types = gantt.config.links;
+		switch (link.type)
+		{
+			case types.finish_to_start:
+				valid = (source.end_date <= target.start_date)
+				break;
+			case types.start_to_start:
+				valid = (source.start_date <= target.start_date);
+				break;
+			case types.finish_to_finish:
+				valid = (source.end_date >= target.end_date);
+				break;
+			case types.start_to_finish:
+				valid = (source.start_date >= target.end_date)
+				break;
+		}
+
+		link_class += valid ? '' : 'invalid_constraint';
+
+		return link_class;
+	}
 });
\ No newline at end of file
diff --git a/etemplate/templates/default/etemplate2.css b/etemplate/templates/default/etemplate2.css
index d9e7e9dfce..f3f2dfbde2 100644
--- a/etemplate/templates/default/etemplate2.css
+++ b/etemplate/templates/default/etemplate2.css
@@ -1448,6 +1448,18 @@ div.ui-toolbar-menulist{
 {
 	background-color: #f7eb91;
 }
+.et2_gantt .gantt_task_link.invalid_constraint .gantt_line_wrapper div
+{
+	background-color: red;
+}
+.et2_gantt .gantt_task_link.invalid_constraint .gantt_link_arrow_left
+{
+	border-right-color: red;
+}
+.et2_gantt .gantt_task_link.invalid_constraint .gantt_link_arrow_right
+{
+	border-left-color: red;
+}
 
 /**
  * Do not wrap content of a single widget incl. a label or children of a hbox.