diff --git a/lib/timeline/component/ClusterGenerator.js b/lib/timeline/component/ClusterGenerator.js
index 6032b590a7..b07c056eab 100644
--- a/lib/timeline/component/ClusterGenerator.js
+++ b/lib/timeline/component/ClusterGenerator.js
@@ -154,7 +154,7 @@ export default class ClusterGenerator {
                             // and calculate the average start for the cluster
                             let m = i;
                             while (clusterItems.length < num && m < items.length) {
-                                if (clusterCriteria(items[m].data, items[m].data)) {
+                                if (clusterCriteria(items[i].data, items[m].data)) {
                                     clusterItems.push(items[m]);
                                 }
                                 m++;
diff --git a/lib/timeline/component/item/ClusterItem.js b/lib/timeline/component/item/ClusterItem.js
index 127f0a9627..48b884730c 100644
--- a/lib/timeline/component/item/ClusterItem.js
+++ b/lib/timeline/component/item/ClusterItem.js
@@ -70,7 +70,7 @@ class ClusterItem extends Item {
   isVisible(range) {
     const rangeWidth = this.data.end ? this.data.end - this.data.start : 0;
     const widthInMs = this.width * range.getMillisecondsPerPixel();
-    const end = Math.max(rangeWidth, this.data.start.getTime() + widthInMs);
+    const end = Math.max(this.data.start.getTime() + rangeWidth, this.data.start.getTime() + widthInMs);
     return (this.data.start < range.end) && (end > range.start) && this.hasItems();
   }