Index: applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/OSMValidatorPlugin.java
===================================================================
--- applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/OSMValidatorPlugin.java	(revision 5246)
+++ applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/OSMValidatorPlugin.java	(revision 5247)
@@ -49,4 +49,5 @@
         UntaggedNode.class, 
         UntaggedWay.class,
+        SelfIntersectingWay.class,
     	SpellCheck.class,
         DuplicatedWayNodes.class, 
Index: applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/tests/SelfIntersectingWay.java
===================================================================
--- applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/tests/SelfIntersectingWay.java	(revision 5247)
+++ applications/editors/josm/plugins/validator/src/org/openstreetmap/josm/plugins/validator/tests/SelfIntersectingWay.java	(revision 5247)
@@ -0,0 +1,36 @@
+package org.openstreetmap.josm.plugins.validator.tests;
+
+import static org.openstreetmap.josm.tools.I18n.tr;
+
+import java.util.HashSet;
+
+import org.openstreetmap.josm.data.osm.Way;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.plugins.validator.Severity;
+import org.openstreetmap.josm.plugins.validator.Test;
+import org.openstreetmap.josm.plugins.validator.TestError;
+
+/**
+ * Checks for self-intersecting ways.
+ */
+public class SelfIntersectingWay extends Test {
+	public SelfIntersectingWay() {
+		super(tr("Self-intersecting ways"),
+			  tr("This test checks for ways " +
+				"that contain some of their nodes more than once"));
+	}
+
+	@Override public void visit(Way w) {
+		HashSet<Node> nodes = new HashSet<Node>();
+
+		for (Node n : w.nodes) {
+			if (nodes.contains(n)) {
+				errors.add(new TestError(this,
+					Severity.WARNING, tr("Self-intersecting ways"), w, 0));
+				break;
+			} else {
+				nodes.add(n);
+			}
+		}
+	}		
+}