diff --git a/packages/core/src/layout/hierarchical/model/mxGraphHierarchyModel.js b/packages/core/src/layout/hierarchical/model/mxGraphHierarchyModel.js
index 08770dd21..1f1d8b426 100644
--- a/packages/core/src/layout/hierarchical/model/mxGraphHierarchyModel.js
+++ b/packages/core/src/layout/hierarchical/model/mxGraphHierarchyModel.js
@@ -8,7 +8,6 @@
 import mxDictionary from '../../../util/datatypes/mxDictionary';
 import mxGraphHierarchyNode from './mxGraphHierarchyNode';
 import mxGraphHierarchyEdge from './mxGraphHierarchyEdge';
-import mxUtils from '../../../util/mxUtils';
 
 /**
  * Class: mxGraphHierarchyModel
@@ -94,12 +93,7 @@ class mxGraphHierarchyModel {
               internalTargetCell.connectsAsTarget = [];
             }
 
-            if (
-              mxUtils.indexOf(
-                internalTargetCell.connectsAsTarget,
-                internalEdge
-              ) < 0
-            ) {
+            if (internalTargetCell.connectsAsTarget.indexOf(internalEdge) < 0) {
               internalTargetCell.connectsAsTarget.push(internalEdge);
             }
           }
@@ -259,12 +253,7 @@ class mxGraphHierarchyModel {
 
             internalEdge.source = internalVertices[i];
 
-            if (
-              mxUtils.indexOf(
-                internalVertices[i].connectsAsSource,
-                internalEdge
-              ) < 0
-            ) {
+            if (internalVertices[i].connectsAsSource.indexOf(internalEdge) < 0) {
               internalVertices[i].connectsAsSource.push(internalEdge);
             }
           }
diff --git a/packages/core/src/layout/hierarchical/model/mxSwimlaneModel.js b/packages/core/src/layout/hierarchical/model/mxSwimlaneModel.js
index 2f7c2e53b..93f5a69da 100644
--- a/packages/core/src/layout/hierarchical/model/mxSwimlaneModel.js
+++ b/packages/core/src/layout/hierarchical/model/mxSwimlaneModel.js
@@ -93,12 +93,7 @@ class mxSwimlaneModel {
               internalTargetCell.connectsAsTarget = [];
             }
 
-            if (
-              mxUtils.indexOf(
-                internalTargetCell.connectsAsTarget,
-                internalEdge
-              ) < 0
-            ) {
+            if (internalTargetCell.connectsAsTarget.indexOf(internalEdge) < 0) {
               internalTargetCell.connectsAsTarget.push(internalEdge);
             }
           }
@@ -274,12 +269,7 @@ class mxSwimlaneModel {
 
             internalEdge.source = internalVertices[i];
 
-            if (
-              mxUtils.indexOf(
-                internalVertices[i].connectsAsSource,
-                internalEdge
-              ) < 0
-            ) {
+            if (internalVertices[i].connectsAsSource.indexOf(internalEdge) < 0) {
               internalVertices[i].connectsAsSource.push(internalEdge);
             }
           }
diff --git a/packages/core/src/serialization/mxChildChangeCodec.js b/packages/core/src/serialization/mxChildChangeCodec.js
index d19e472c9..de38042ca 100644
--- a/packages/core/src/serialization/mxChildChangeCodec.js
+++ b/packages/core/src/serialization/mxChildChangeCodec.js
@@ -8,7 +8,6 @@
 import mxChildChange from '../atomic_changes/mxChildChange';
 import mxObjectCodec from './mxObjectCodec';
 import mxCodecRegistry from './mxCodecRegistry';
-import mxUtils from '../util/mxUtils';
 import mxConstants from '../util/mxConstants';
 
 /**
@@ -50,7 +49,7 @@ class mxChildChangeCodec extends mxObjectCodec {
     if (attr === 'child' && (!isWrite || obj.model.contains(obj.previous))) {
       return true;
     }
-    return mxUtils.indexOf(this.idrefs, attr) >= 0;
+    return this.idrefs.indexOf(attr) >= 0;
   }
 
   /**
diff --git a/packages/core/src/serialization/mxObjectCodec.js b/packages/core/src/serialization/mxObjectCodec.js
index 85c9d5cf4..68af98594 100644
--- a/packages/core/src/serialization/mxObjectCodec.js
+++ b/packages/core/src/serialization/mxObjectCodec.js
@@ -314,7 +314,7 @@ class mxObjectCodec {
   isExcluded(obj, attr, value, write) {
     return (
       attr == mxObjectIdentity.FIELD_NAME ||
-      mxUtils.indexOf(this.exclude, attr) >= 0
+      this.exclude.indexOf(attr) >= 0
     );
   }
 
@@ -331,7 +331,7 @@ class mxObjectCodec {
    */
   // isReference(obj: any, attr: string, value: any, write?: boolean): boolean;
   isReference(obj, attr, value, write) {
-    return mxUtils.indexOf(this.idrefs, attr) >= 0;
+    return this.idrefs.indexOf(attr) >= 0;
   }
 
   /**
diff --git a/packages/core/src/shape/mxShape.ts b/packages/core/src/shape/mxShape.ts
index 677483070..805087669 100644
--- a/packages/core/src/shape/mxShape.ts
+++ b/packages/core/src/shape/mxShape.ts
@@ -1045,7 +1045,7 @@ class mxShape {
         if (
           rounded &&
           (dx !== 0 || dy !== 0) &&
-          (exclude == null || mxUtils.indexOf(exclude, i - 1) < 0)
+          (exclude == null || exclude.indexOf(i - 1) < 0)
         ) {
           // Draws a line from the last point to the current
           // point with a spacing of size off the current point
diff --git a/packages/core/src/util/mxResources.js b/packages/core/src/util/mxResources.js
index 189d3751a..3fafa09ab 100644
--- a/packages/core/src/util/mxResources.js
+++ b/packages/core/src/util/mxResources.js
@@ -109,7 +109,7 @@ const mxResources = {
    */
   isLanguageSupported: lan => {
     if (mxClient.languages != null) {
-      return mxUtils.indexOf(mxClient.languages, lan) >= 0;
+      return mxClient.languages.indexOf(lan) >= 0;
     }
 
     return true;
diff --git a/packages/core/src/util/mxUtils.js b/packages/core/src/util/mxUtils.js
index 446b28040..ad6dc12af 100644
--- a/packages/core/src/util/mxUtils.js
+++ b/packages/core/src/util/mxUtils.js
@@ -189,29 +189,6 @@ const mxUtils = {
     return null;
   },
 
-  /**
-   * Function: indexOf
-   *
-   * Returns the index of obj in array or -1 if the array does not contain
-   * the given object.
-   *
-   * Parameters:
-   *
-   * array - Array to check for the given obj.
-   * obj - Object to find in the given array.
-   */
-  indexOf: (array, obj) => {
-    if (array != null && obj != null) {
-      for (let i = 0; i < array.length; i += 1) {
-        if (array[i] == obj) {
-          return i;
-        }
-      }
-    }
-
-    return -1;
-  },
-
   /**
    * Function: forEach
    *
@@ -254,12 +231,12 @@ const mxUtils = {
     let result = null;
 
     if (typeof array === 'object') {
-      let index = mxUtils.indexOf(array, obj);
+      let index = array.indexOf(obj);
 
       while (index >= 0) {
         array.splice(index, 1);
         result = obj;
-        index = mxUtils.indexOf(array, obj);
+        index = array.indexOf(obj);
       }
     }
 
diff --git a/packages/core/src/view/cell/mxCell.ts b/packages/core/src/view/cell/mxCell.ts
index c1164604e..ad2192609 100644
--- a/packages/core/src/view/cell/mxCell.ts
+++ b/packages/core/src/view/cell/mxCell.ts
@@ -438,7 +438,8 @@ class mxCell {
    */
   // getIndex(child: mxCell): number;
   getIndex(child: mxCell | null): number {
-    return mxUtils.indexOf(this.children, child);
+    if (child === null || !this.children) return -1;
+    return this.children.indexOf(child);
   }
 
   /**
@@ -540,7 +541,8 @@ class mxCell {
    */
   // getEdgeIndex(edge: mxCell): number;
   getEdgeIndex(edge: mxCell): number {
-    return mxUtils.indexOf(this.edges, edge);
+    if (!this.edges) return -1;
+    return this.edges.indexOf(edge);
   }
 
   /**
@@ -573,7 +575,7 @@ class mxCell {
       if (
         this.edges == null ||
         edge.getTerminal(!isOutgoing) !== this ||
-        mxUtils.indexOf(this.edges, edge) < 0
+        this.edges.indexOf(edge) < 0
       ) {
         if (this.edges == null) {
           this.edges = [];
diff --git a/packages/core/src/view/cell/mxCellRenderer.ts b/packages/core/src/view/cell/mxCellRenderer.ts
index 2f08f29a2..29263bd8f 100644
--- a/packages/core/src/view/cell/mxCellRenderer.ts
+++ b/packages/core/src/view/cell/mxCellRenderer.ts
@@ -316,7 +316,7 @@ class mxCellRenderer {
       ];
 
       for (let i = 0; i < styles.length; i += 1) {
-        if (mxUtils.indexOf(values, state.style[styles[i]]) >= 0) {
+        if (values.indexOf(state.style[styles[i]]) >= 0) {
           return true;
         }
       }
diff --git a/packages/core/src/view/graph/mxGraph.ts b/packages/core/src/view/graph/mxGraph.ts
index 3efe7ea88..e36ee6f0d 100644
--- a/packages/core/src/view/graph/mxGraph.ts
+++ b/packages/core/src/view/graph/mxGraph.ts
@@ -1511,7 +1511,7 @@ class mxGraph extends mxEventSource {
     if (overlay == null) {
       this.removeCellOverlays(cell);
     } else {
-      const index = mxUtils.indexOf(cell.overlays, overlay);
+      const index = cell.overlays ? cell.overlays.indexOf(overlay) : -1;
 
       if (index >= 0) {
         (<mxCellOverlay[]>cell.overlays).splice(index, 1);
@@ -6708,7 +6708,7 @@ class mxGraph extends mxEventSource {
                       geo.height
                     );
 
-                    if (mxUtils.indexOf(cells, parent) >= 0) {
+                    if (cells.indexOf(parent) >= 0) {
                       bbox.x += tmp.x;
                       bbox.y += tmp.y;
                     }
@@ -6719,7 +6719,7 @@ class mxGraph extends mxEventSource {
 
                 if (
                   parent.isVertex() &&
-                  mxUtils.indexOf(cells, parent) >= 0
+                  cells.indexOf(parent) >= 0
                 ) {
                   tmp = this.getBoundingBoxFromGeometry([parent], false);
 
@@ -9766,7 +9766,7 @@ class mxGraph extends mxEventSource {
     // Checks if parent is dropped into child if not cloning
     if (!clone) {
       let parent = cell;
-      while (parent != null && mxUtils.indexOf(cells, parent) < 0) {
+      while (parent != null && cells.indexOf(parent) < 0) {
         parent = parent.getParent();
       }
     }
diff --git a/packages/core/src/view/graph/mxGraphSelectionModel.ts b/packages/core/src/view/graph/mxGraphSelectionModel.ts
index 1b7fc5867..e6e9f9619 100644
--- a/packages/core/src/view/graph/mxGraphSelectionModel.ts
+++ b/packages/core/src/view/graph/mxGraphSelectionModel.ts
@@ -113,7 +113,7 @@ class mxGraphSelectionModel extends mxEventSource {
   // isSelected(cell: mxCell): boolean;
   isSelected(cell: mxCell): boolean {
     if (cell != null) {
-      return mxUtils.indexOf(this.cells, cell) >= 0;
+      return this.cells.indexOf(cell) >= 0;
     }
     return false;
   }
@@ -302,7 +302,7 @@ class mxGraphSelectionModel extends mxEventSource {
   // cellRemoved(cell: mxCell): void;
   cellRemoved(cell: mxCell): void {
     if (cell != null) {
-      const index = mxUtils.indexOf(this.cells, cell);
+      const index = this.cells.indexOf(cell);
       if (index >= 0) {
         this.cells.splice(index, 1);
       }
diff --git a/packages/html/stories/Clipboard.stories.js b/packages/html/stories/Clipboard.stories.js
index cc10ce345..546922cd0 100644
--- a/packages/html/stories/Clipboard.stories.js
+++ b/packages/html/stories/Clipboard.stories.js
@@ -282,15 +282,13 @@ const Template = ({ label, ...args }) => {
 
       if (provider != null) {
         data =
-          mxUtils.indexOf(provider.types, 'text/html') >= 0
+          provider.types.indexOf('text/html') >= 0
             ? provider.getData('text/html')
             : null;
 
         if (
-          mxUtils.indexOf(
-            provider.types,
-            'text/plain' && (data == null || data.length === 0)
-          )
+          provider.types.indexOf('text/plain')
+          && (data == null || data.length === 0)
         ) {
           data = provider.getData('text/plain');
         }