diff --git a/CHANGELOG.MD b/CHANGELOG.MD
index 5abc457..886f434 100644
--- a/CHANGELOG.MD
+++ b/CHANGELOG.MD
@@ -1,5 +1,8 @@
 # Changelog
 
+### 15.6.1 (*2022-08-12*)
+- Fixed: (Typescript) type for keys in `range` (#1218);
+
 ### 15.6.0 (*2022-05-01*)
 - Added: `smooth-steps` `behaviour` flag (#627);
 
diff --git a/dist/nouislider.d.ts b/dist/nouislider.d.ts
index ea575ee..5a2832c 100644
--- a/dist/nouislider.d.ts
+++ b/dist/nouislider.d.ts
@@ -61,7 +61,7 @@ declare type SubRange = number | WrappedSubRange;
 interface Range {
     min: SubRange;
     max: SubRange;
-    [key: string]: SubRange;
+    [key: `${number}%`]: SubRange;
 }
 interface BasePips {
     mode: PipsMode;
diff --git a/package-lock.json b/package-lock.json
index eb5295b..2309800 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "nouislider",
-  "version": "15.6.0",
+  "version": "15.6.1",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "nouislider",
-      "version": "15.6.0",
+      "version": "15.6.1",
       "license": "MIT",
       "devDependencies": {
         "@typescript-eslint/eslint-plugin": "^5.10",
diff --git a/package.json b/package.json
index 0596357..4cddf45 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "nouislider",
-  "version": "15.6.0",
+  "version": "15.6.1",
   "main": "dist/nouislider.js",
   "style": "dist/nouislider.min.css",
   "types": "dist/nouislider.d.ts",
diff --git a/src/nouislider.ts b/src/nouislider.ts
index c7dec07..620a5fe 100644
--- a/src/nouislider.ts
+++ b/src/nouislider.ts
@@ -583,7 +583,7 @@ class Spectrum {
         const ordered: [WrappedSubRange, string][] = [];
 
         // Map the object keys to an array.
-        Object.keys(entry).forEach((index) => {
+        Object.keys(entry).forEach((index: keyof Range) => {
             ordered.push([asArray(entry[index]) as WrappedSubRange, index]);
         });