diff --git a/lib/collections/unordered-map.d.ts b/lib/collections/unordered-map.d.ts
index 609bae4be..eb31a8833 100644
--- a/lib/collections/unordered-map.d.ts
+++ b/lib/collections/unordered-map.d.ts
@@ -9,9 +9,6 @@ export declare class UnorderedMap {
     constructor(prefix: Bytes);
     len(): number;
     isEmpty(): boolean;
-    serializeIndex(index: number): Bytes;
-    deserializeIndex(rawIndex: Bytes): number;
-    getIndexRaw(key: Bytes): Bytes;
     get(key: Bytes): unknown | null;
     set(key: Bytes, value: unknown): unknown | null;
     remove(key: Bytes): unknown | null;
diff --git a/lib/collections/unordered-map.js b/lib/collections/unordered-map.js
index 3cb0d1809..b644d262f 100644
--- a/lib/collections/unordered-map.js
+++ b/lib/collections/unordered-map.js
@@ -2,6 +2,21 @@ import * as near from "../api";
 import { u8ArrayToBytes, bytesToU8Array } from "../utils";
 import { Vector, VectorIterator } from "./vector";
 const ERR_INCONSISTENT_STATE = "The collection is an inconsistent state. Did previous smart contract execution terminate unexpectedly?";
+function serializeIndex(index) {
+    let data = new Uint32Array([index]);
+    let array = new Uint8Array(data.buffer);
+    return u8ArrayToBytes(array);
+}
+function deserializeIndex(rawIndex) {
+    let array = bytesToU8Array(rawIndex);
+    let data = new Uint32Array(array.buffer);
+    return data[0];
+}
+function getIndexRaw(keyIndexPrefix, key) {
+    let indexLookup = keyIndexPrefix + JSON.stringify(key);
+    let indexRaw = near.storageRead(indexLookup);
+    return indexRaw;
+}
 export class UnorderedMap {
     constructor(prefix) {
         this.length = 0;
@@ -28,25 +43,10 @@ export class UnorderedMap {
         }
         return keysIsEmpty;
     }
-    serializeIndex(index) {
-        let data = new Uint32Array([index]);
-        let array = new Uint8Array(data.buffer);
-        return u8ArrayToBytes(array);
-    }
-    deserializeIndex(rawIndex) {
-        let array = bytesToU8Array(rawIndex);
-        let data = new Uint32Array(array.buffer);
-        return data[0];
-    }
-    getIndexRaw(key) {
-        let indexLookup = this.keyIndexPrefix + JSON.stringify(key);
-        let indexRaw = near.storageRead(indexLookup);
-        return indexRaw;
-    }
     get(key) {
-        let indexRaw = this.getIndexRaw(key);
+        let indexRaw = getIndexRaw(this.keyIndexPrefix, key);
         if (indexRaw) {
-            let index = this.deserializeIndex(indexRaw);
+            let index = deserializeIndex(indexRaw);
             let value = this.values.get(index);
             if (value) {
                 return value;
@@ -61,12 +61,12 @@ export class UnorderedMap {
         let indexLookup = this.keyIndexPrefix + JSON.stringify(key);
         let indexRaw = near.storageRead(indexLookup);
         if (indexRaw) {
-            let index = this.deserializeIndex(indexRaw);
+            let index = deserializeIndex(indexRaw);
             return this.values.replace(index, value);
         }
         else {
             let nextIndex = this.len();
-            let nextIndexRaw = this.serializeIndex(nextIndex);
+            let nextIndexRaw = serializeIndex(nextIndex);
             near.storageWrite(indexLookup, nextIndexRaw);
             this.keys.push(key);
             this.values.push(value);
@@ -97,7 +97,7 @@ export class UnorderedMap {
                     near.storageWrite(lastLookupKey, indexRaw);
                 }
             }
-            let index = this.deserializeIndex(indexRaw);
+            let index = deserializeIndex(indexRaw);
             this.keys.swapRemove(index);
             return this.values.swapRemove(index);
         }
diff --git a/lib/collections/unordered-set.d.ts b/lib/collections/unordered-set.d.ts
index b1be5ac5d..4db030d97 100644
--- a/lib/collections/unordered-set.d.ts
+++ b/lib/collections/unordered-set.d.ts
@@ -8,8 +8,6 @@ export declare class UnorderedSet {
     constructor(prefix: Bytes);
     len(): number;
     isEmpty(): boolean;
-    serializeIndex(index: number): string;
-    deserializeIndex(rawIndex: Bytes): number;
     contains(element: unknown): boolean;
     set(element: unknown): boolean;
     remove(element: unknown): boolean;
diff --git a/lib/collections/unordered-set.js b/lib/collections/unordered-set.js
index f36704b09..5466bc866 100644
--- a/lib/collections/unordered-set.js
+++ b/lib/collections/unordered-set.js
@@ -2,6 +2,16 @@ import * as near from "../api";
 import { u8ArrayToBytes, bytesToU8Array } from "../utils";
 import { Vector } from "./vector";
 const ERR_INCONSISTENT_STATE = "The collection is an inconsistent state. Did previous smart contract execution terminate unexpectedly?";
+function serializeIndex(index) {
+    let data = new Uint32Array([index]);
+    let array = new Uint8Array(data.buffer);
+    return u8ArrayToBytes(array);
+}
+function deserializeIndex(rawIndex) {
+    let array = bytesToU8Array(rawIndex);
+    let data = new Uint32Array(array.buffer);
+    return data[0];
+}
 export class UnorderedSet {
     constructor(prefix) {
         this.length = 0;
@@ -16,16 +26,6 @@ export class UnorderedSet {
     isEmpty() {
         return this.elements.isEmpty();
     }
-    serializeIndex(index) {
-        let data = new Uint32Array([index]);
-        let array = new Uint8Array(data.buffer);
-        return u8ArrayToBytes(array);
-    }
-    deserializeIndex(rawIndex) {
-        let array = bytesToU8Array(rawIndex);
-        let data = new Uint32Array(array.buffer);
-        return data[0];
-    }
     contains(element) {
         let indexLookup = this.elementIndexPrefix + JSON.stringify(element);
         return near.storageHasKey(indexLookup);
@@ -37,7 +37,7 @@ export class UnorderedSet {
         }
         else {
             let nextIndex = this.len();
-            let nextIndexRaw = this.serializeIndex(nextIndex);
+            let nextIndexRaw = serializeIndex(nextIndex);
             near.storageWrite(indexLookup, nextIndexRaw);
             this.elements.push(element);
             return true;
@@ -67,7 +67,7 @@ export class UnorderedSet {
                     near.storageWrite(lastLookupElement, indexRaw);
                 }
             }
-            let index = this.deserializeIndex(indexRaw);
+            let index = deserializeIndex(indexRaw);
             this.elements.swapRemove(index);
             return true;
         }
diff --git a/src/collections/unordered-map.ts b/src/collections/unordered-map.ts
index d36072cfa..f18abd3c7 100644
--- a/src/collections/unordered-map.ts
+++ b/src/collections/unordered-map.ts
@@ -5,6 +5,24 @@ import { Vector, VectorIterator } from "./vector";
 const ERR_INCONSISTENT_STATE =
   "The collection is an inconsistent state. Did previous smart contract execution terminate unexpectedly?";
 
+function serializeIndex(index: number): Bytes {
+  let data = new Uint32Array([index]);
+  let array = new Uint8Array(data.buffer);
+  return u8ArrayToBytes(array);
+}
+
+function deserializeIndex(rawIndex: Bytes) {
+  let array = bytesToU8Array(rawIndex);
+  let data = new Uint32Array(array.buffer);
+  return data[0];
+}
+
+function getIndexRaw(keyIndexPrefix: Bytes, key: Bytes): Bytes {
+  let indexLookup = keyIndexPrefix + JSON.stringify(key);
+  let indexRaw = near.storageRead(indexLookup);
+  return indexRaw;
+}
+
 export class UnorderedMap {
   readonly length: number;
   readonly prefix: Bytes;
@@ -40,28 +58,10 @@ export class UnorderedMap {
     return keysIsEmpty;
   }
 
-  serializeIndex(index: number): Bytes {
-    let data = new Uint32Array([index]);
-    let array = new Uint8Array(data.buffer);
-    return u8ArrayToBytes(array);
-  }
-
-  deserializeIndex(rawIndex: Bytes) {
-    let array = bytesToU8Array(rawIndex);
-    let data = new Uint32Array(array.buffer);
-    return data[0];
-  }
-
-  getIndexRaw(key: Bytes): Bytes {
-    let indexLookup = this.keyIndexPrefix + JSON.stringify(key);
-    let indexRaw = near.storageRead(indexLookup);
-    return indexRaw;
-  }
-
   get(key: Bytes): unknown | null {
-    let indexRaw = this.getIndexRaw(key);
+    let indexRaw = getIndexRaw(this.keyIndexPrefix, key);
     if (indexRaw) {
-      let index = this.deserializeIndex(indexRaw);
+      let index = deserializeIndex(indexRaw);
       let value = this.values.get(index);
       if (value) {
         return value;
@@ -76,11 +76,11 @@ export class UnorderedMap {
     let indexLookup = this.keyIndexPrefix + JSON.stringify(key);
     let indexRaw = near.storageRead(indexLookup);
     if (indexRaw) {
-      let index = this.deserializeIndex(indexRaw);
+      let index = deserializeIndex(indexRaw);
       return this.values.replace(index, value);
     } else {
       let nextIndex = this.len();
-      let nextIndexRaw = this.serializeIndex(nextIndex);
+      let nextIndexRaw = serializeIndex(nextIndex);
       near.storageWrite(indexLookup, nextIndexRaw);
       this.keys.push(key);
       this.values.push(value);
@@ -111,7 +111,7 @@ export class UnorderedMap {
           near.storageWrite(lastLookupKey, indexRaw);
         }
       }
-      let index = this.deserializeIndex(indexRaw);
+      let index = deserializeIndex(indexRaw);
       this.keys.swapRemove(index);
       return this.values.swapRemove(index);
     }
@@ -162,7 +162,7 @@ export class UnorderedMap {
     // reconstruct values Vector
     map.values = new Vector(data.prefix + "v");
     map.values.length = data.values.length;
-    return map;
+    return map as UnorderedMap;
   }
 }
 
diff --git a/src/collections/unordered-set.ts b/src/collections/unordered-set.ts
index 1094f11ae..2df62eaf1 100644
--- a/src/collections/unordered-set.ts
+++ b/src/collections/unordered-set.ts
@@ -6,6 +6,18 @@ import { Mutable } from "../utils";
 const ERR_INCONSISTENT_STATE =
   "The collection is an inconsistent state. Did previous smart contract execution terminate unexpectedly?";
 
+function serializeIndex(index: number) {
+  let data = new Uint32Array([index]);
+  let array = new Uint8Array(data.buffer);
+  return u8ArrayToBytes(array);
+}
+
+function deserializeIndex(rawIndex: Bytes): number {
+  let array = bytesToU8Array(rawIndex);
+  let data = new Uint32Array(array.buffer);
+  return data[0];
+}
+
 export class UnorderedSet {
   readonly length: number;
   readonly prefix: Bytes;
@@ -28,18 +40,6 @@ export class UnorderedSet {
     return this.elements.isEmpty();
   }
 
-  serializeIndex(index: number) {
-    let data = new Uint32Array([index]);
-    let array = new Uint8Array(data.buffer);
-    return u8ArrayToBytes(array);
-  }
-
-  deserializeIndex(rawIndex: Bytes): number {
-    let array = bytesToU8Array(rawIndex);
-    let data = new Uint32Array(array.buffer);
-    return data[0];
-  }
-
   contains(element: unknown): boolean {
     let indexLookup = this.elementIndexPrefix + JSON.stringify(element);
     return near.storageHasKey(indexLookup);
@@ -51,7 +51,7 @@ export class UnorderedSet {
       return false;
     } else {
       let nextIndex = this.len();
-      let nextIndexRaw = this.serializeIndex(nextIndex);
+      let nextIndexRaw = serializeIndex(nextIndex);
       near.storageWrite(indexLookup, nextIndexRaw);
       this.elements.push(element);
       return true;
@@ -81,7 +81,7 @@ export class UnorderedSet {
           near.storageWrite(lastLookupElement, indexRaw);
         }
       }
-      let index = this.deserializeIndex(indexRaw);
+      let index = deserializeIndex(indexRaw);
       this.elements.swapRemove(index);
       return true;
     }
@@ -129,6 +129,6 @@ export class UnorderedSet {
     let elementsPrefix = data.prefix + "e";
     set.elements = new Vector(elementsPrefix);
     set.elements.length = data.elements.length;
-    return set;
+    return set as UnorderedSet;
   }
 }
diff --git a/tests/jsconfig.json b/tests/jsconfig.json
index d49b02077..e4e17cc70 100644
--- a/tests/jsconfig.json
+++ b/tests/jsconfig.json
@@ -1,8 +1,8 @@
 {
     "compilerOptions": {
-        "experimentalDecorators": true,
+        "experimentalDecorators": true
     },
     "exclude": [
         "node_modules"
-    ],
+    ]
 }
\ No newline at end of file
diff --git a/tests/src/unordered-map.js b/tests/src/unordered-map.js
index 639dc4066..aa70f09a1 100644
--- a/tests/src/unordered-map.js
+++ b/tests/src/unordered-map.js
@@ -29,21 +29,6 @@ class UnorderedMapTestContract extends NearContract {
         return this.unorderedMap.isEmpty();
     }
 
-    @view
-    serializeIndex({index}) {
-        return this.unorderedMap.serializeIndex(index);
-    }
-
-    @view
-    deserializeIndex({rawIndex}) {
-        return this.unorderedMap.deserializeIndex(rawIndex);
-    }
-
-    @view
-    getIndexRaw({key}) {
-        return this.unorderedMap.getIndexRaw(key);
-    }
-
     @view
     get({key}) {
         return this.unorderedMap.get(key);