diff --git a/client/app/scripts/charts/__tests__/node-layout-test.js b/client/app/scripts/charts/__tests__/node-layout-test.js
index 078a16958..69aba50a1 100644
--- a/client/app/scripts/charts/__tests__/node-layout-test.js
+++ b/client/app/scripts/charts/__tests__/node-layout-test.js
@@ -74,6 +74,31 @@ describe('NodesLayout', () => {
     };
   });
 
+  it('detects unseen nodes', () => {
+    const set1 = fromJS({
+      n1: {id: 'n1'}
+    });
+    const set12 = fromJS({
+      n1: {id: 'n1'},
+      n2: {id: 'n2'}
+    });
+    const set13 = fromJS({
+      n1: {id: 'n1'},
+      n3: {id: 'n3'}
+    });
+    let hasUnseen;
+    hasUnseen = NodesLayout.hasUnseenNodes(set12, set1);
+    expect(hasUnseen).toBeTruthy();
+    hasUnseen = NodesLayout.hasUnseenNodes(set13, set1);
+    expect(hasUnseen).toBeTruthy();
+    hasUnseen = NodesLayout.hasUnseenNodes(set1, set12);
+    expect(hasUnseen).toBeFalsy();
+    hasUnseen = NodesLayout.hasUnseenNodes(set1, set13);
+    expect(hasUnseen).toBeFalsy();
+    hasUnseen = NodesLayout.hasUnseenNodes(set12, set13);
+    expect(hasUnseen).toBeTruthy();
+  });
+
   it('lays out initial nodeset in a rectangle', () => {
     const result = NodesLayout.doLayout(
       nodeSets.initial4.nodes,
diff --git a/client/app/scripts/charts/nodes-layout.js b/client/app/scripts/charts/nodes-layout.js
index 0dfae60ae..635bfd64f 100644
--- a/client/app/scripts/charts/nodes-layout.js
+++ b/client/app/scripts/charts/nodes-layout.js
@@ -144,9 +144,13 @@ function setSimpleEdgePoints(edge, nodeCache) {
  * @param  {Map} cache     old Map of nodes
  * @return {Boolean}       True if nodes had node ids that are not in cache
  */
-function hasUnseenNodes(nodes, cache) {
-  return (nodes.size > cache.size
-    || !ImmSet.fromKeys(nodes).isSubset(ImmSet.fromKeys(nodes)));
+export function hasUnseenNodes(nodes, cache) {
+  const hasUnseen = nodes.size > cache.size
+    || !ImmSet.fromKeys(nodes).isSubset(ImmSet.fromKeys(cache));
+  if (hasUnseen) {
+    debug('unseen nodes:', ...ImmSet.fromKeys(nodes).subtract(ImmSet.fromKeys(cache)).toJS());
+  }
+  return hasUnseen;
 }
 
 /**