diff --git a/umap/static/umap/js/modules/ui/base.js b/umap/static/umap/js/modules/ui/base.js
index 4f0c176c..50b55487 100644
--- a/umap/static/umap/js/modules/ui/base.js
+++ b/umap/static/umap/js/modules/ui/base.js
@@ -63,6 +63,22 @@ export class Positioned {
     else this.container.style.bottom = 'initial'
   }
 
+  computePosition([x, y]) {
+    let left
+    let top
+    if (x < window.innerWidth / 2) {
+      left = x
+    } else {
+      left = x - this.container.offsetWidth
+    }
+    if (y < window.innerHeight / 2) {
+      top = y
+    } else {
+      top = y - this.container.offsetHeight
+    }
+    this.setPosition({ left, top })
+  }
+
   getDocHeight() {
     const D = document
     return Math.max(
diff --git a/umap/static/umap/js/modules/ui/contextmenu.js b/umap/static/umap/js/modules/ui/contextmenu.js
index 65516055..1ff33a5d 100644
--- a/umap/static/umap/js/modules/ui/contextmenu.js
+++ b/umap/static/umap/js/modules/ui/contextmenu.js
@@ -1,7 +1,9 @@
 import { loadTemplate } from '../utils.js'
+import { Positioned } from './base.js'
 
-export default class ContextMenu {
+export default class ContextMenu extends Positioned {
   constructor(options = {}) {
+    super()
     this.options = options
     this.container = document.createElement('ul')
     this.container.className = 'umap-contextmenu'
@@ -26,7 +28,7 @@ export default class ContextMenu {
       this.container.appendChild(li)
     }
     document.body.appendChild(this.container)
-    this.setPosition([x, y], this.container)
+    this.computePosition([x, y])
     this.container.querySelector('button').focus()
     this.container.addEventListener('keydown', (event) => {
       if (event.key === 'Escape') {
@@ -36,19 +38,6 @@ export default class ContextMenu {
     })
   }
 
-  setPosition([x, y], element) {
-    if (x < window.innerWidth / 2) {
-      this.container.style.left = `${x}px`
-    } else {
-      this.container.style.left = `${x - element.offsetWidth}px`
-    }
-    if (y < window.innerHeight / 2) {
-      this.container.style.top = `${y}px`
-    } else {
-      this.container.style.top = `${y - element.offsetHeight}px`
-    }
-  }
-
   close() {
     try {
       this.container.remove()