Index: /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 11107)
+++ /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 11108)
@@ -104,17 +104,16 @@
         if (size == 0)
             throw new IllegalArgumentException("empty list");
+        if (size == 1) // to avoid division by 0 in mode 2
+            return candidates.get(0);
 
         switch (Main.pref.getInteger("merge-nodes.mode", 0)) {
         case 0:
-            Node targetNode = candidates.get(size - 1);
-            for (final Node n : candidates) { // pick last one
-                targetNode = n;
-            }
-            return targetNode;
+            return candidates.get(size - 1);
         case 1:
             double east1 = 0, north1 = 0;
             for (final Node n : candidates) {
-                east1 += n.getEastNorth().east();
-                north1 += n.getEastNorth().north();
+                EastNorth en = n.getEastNorth();
+                east1 += en.east();
+                north1 += en.north();
             }
 
Index: /trunk/test/unit/org/openstreetmap/josm/actions/MergeNodesActionTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/actions/MergeNodesActionTest.java	(revision 11108)
+++ /trunk/test/unit/org/openstreetmap/josm/actions/MergeNodesActionTest.java	(revision 11108)
@@ -0,0 +1,75 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.actions;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.openstreetmap.josm.Main;
+import org.openstreetmap.josm.data.coor.LatLon;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.testutils.JOSMTestRules;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
+/**
+ * Unit tests for class {@link MergeNodesAction}.
+ */
+public class MergeNodesActionTest {
+
+    /**
+     * Setup test.
+     */
+    @Rule
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public JOSMTestRules test = new JOSMTestRules().platform().commands();
+
+    /**
+     * Unit test of {@link MergeNodesAction#selectTargetLocationNode} - empty list
+     */
+    @Test(expected = IllegalArgumentException.class)
+    public void testSelectTargetLocationNodeEmpty() {
+        MergeNodesAction.selectTargetLocationNode(Collections.emptyList());
+    }
+
+    /**
+     * Unit test of {@link MergeNodesAction#selectTargetLocationNode} - invalid mode
+     */
+    @Test(expected = IllegalStateException.class)
+    public void testSelectTargetLocationNodeInvalidMode() {
+        Main.pref.putInteger("merge-nodes.mode", -1);
+        MergeNodesAction.selectTargetLocationNode(Arrays.asList(new Node(0), new Node(1)));
+    }
+
+    /**
+     * Unit test of {@link MergeNodesAction#selectTargetLocationNode} - mode 0
+     */
+    @Test
+    public void testSelectTargetLocationNodeMode0() {
+        Main.pref.putInteger("merge-nodes.mode", 0);
+        assertEquals(1, MergeNodesAction.selectTargetLocationNode(Arrays.asList(new Node(0), new Node(1))).getId());
+    }
+
+    /**
+     * Unit test of {@link MergeNodesAction#selectTargetLocationNode} - mode 1
+     */
+    @Test
+    public void testSelectTargetLocationNodeMode1() {
+        Main.pref.putInteger("merge-nodes.mode", 1);
+        assertEquals(LatLon.ZERO, MergeNodesAction.selectTargetLocationNode(
+                Arrays.asList(new Node(LatLon.NORTH_POLE), new Node(LatLon.SOUTH_POLE))).getCoor());
+    }
+
+    /**
+     * Unit test of {@link MergeNodesAction#selectTargetLocationNode} - mode 2 with a single node
+     */
+    @Test
+    public void testSelectTargetLocationNodeMode2SingleNode() {
+        Main.pref.putInteger("merge-nodes.mode", 2);
+        assertEquals(LatLon.NORTH_POLE, MergeNodesAction.selectTargetLocationNode(
+                Arrays.asList(new Node(LatLon.NORTH_POLE))).getCoor());
+    }
+}