diff --git a/umap/static/umap/js/modules/utils.js b/umap/static/umap/js/modules/utils.js
index 03081308..aa681602 100644
--- a/umap/static/umap/js/modules/utils.js
+++ b/umap/static/umap/js/modules/utils.js
@@ -1,7 +1,7 @@
 /**
- * Generate a pseudo-unique identifier (4 chars long)
+ * Generate a pseudo-unique identifier (5 chars long, mixed-case alphanumeric)
  *
- * Using uppercase + lowercase + digits, here's the collision risk:
+ * Here's the collision risk:
  * - for 6 chars, 1 in 100 000
  * - for 5 chars, 5 in 100 000
  * - for 4 chars, 500 in 100 000
@@ -9,5 +9,5 @@
  * @returns string
  */
 export function generateId() {
-  return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1)
+  return btoa(Math.random().toString()).substring(10, 15)
 }