diff --git a/js/id/actions/split_way.js b/js/id/actions/split_way.js
index 6db8b57e0..6fbd08595 100644
--- a/js/id/actions/split_way.js
+++ b/js/id/actions/split_way.js
@@ -47,7 +47,8 @@ iD.actions.SplitWay = function(nodeId, newWayId) {
                     j;
 
                 for (j = 0; j < relation.members.length; j++) {
-                    if (relation.members[j].type === 'way' && graph.entity(relation.members[j].id).contains(last)) {
+                    var entity = graph.entity(relation.members[j].id);
+                    if (entity && entity.type === 'way' && entity.contains(last)) {
                         break;
                     }
                 }
diff --git a/test/spec/actions/split_way.js b/test/spec/actions/split_way.js
index 6074cbaa8..2958521a9 100644
--- a/test/spec/actions/split_way.js
+++ b/test/spec/actions/split_way.js
@@ -175,6 +175,20 @@ describe("iD.actions.SplitWay", function () {
         expect(_.pluck(graph.entity('r').members, 'id')).to.eql(['~', '=', '-']);
     });
 
+    it("handles incomplete relations", function () {
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b', 'c']}),
+                'r': iD.Relation({id: 'r', members: [{id: '~', type: 'way'}, {id: '-', type: 'way'}]})
+            });
+
+        graph = iD.actions.SplitWay('b', '=')(graph);
+
+        expect(_.pluck(graph.entity('r').members, 'id')).to.eql(['~', '-', '=']);
+    });
+
     ['restriction', 'restriction:bus'].forEach(function (type) {
         it("updates a restriction's 'from' role", function () {
             // Situation: