diff --git a/src/createXcmTypes/SystemToSystem.ts b/src/createXcmTypes/SystemToSystem.ts
index 731f9f2b..8b6c4645 100644
--- a/src/createXcmTypes/SystemToSystem.ts
+++ b/src/createXcmTypes/SystemToSystem.ts
@@ -6,6 +6,7 @@ import type { WeightLimitV2 } from '@polkadot/types/interfaces';
 
 import { BaseError, BaseErrorsEnum } from '../errors';
 import type { Registry } from '../registry';
+import { RequireOnlyOne } from '../types';
 import { getFeeAssetItemIndex } from '../util/getFeeAssetItemIndex';
 import { normalizeArrToStr } from '../util/normalizeArrToStr';
 import { resolveMultiLocation } from '../util/resolveMultiLocation';
@@ -20,6 +21,8 @@ import {
 	UnionXcmMultiAssets,
 	UnionXcmMultiLocation,
 	XcmBase,
+	XcmV2Junctions,
+	XcmV3Junctions,
 } from './types';
 import { dedupeMultiAssets } from './util/dedupeMultiAssets';
 import { fetchPalletInstanceId } from './util/fetchPalletInstanceId';
@@ -275,7 +278,7 @@ export const createSystemToSystemMultiAssets = async (
 			concreteMultiLocation = resolveMultiLocation(
 				{
 					parents: assetIdMultiLocation.parents,
-					interior: JSON.parse(interiorMultiLocationStr),
+					interior: JSON.parse(interiorMultiLocationStr) as RequireOnlyOne<XcmV3Junctions | XcmV2Junctions>,
 				},
 				xcmVersion
 			);
diff --git a/src/createXcmTypes/util/constructForeignAssetMultiLocationFromAssetId.ts b/src/createXcmTypes/util/constructForeignAssetMultiLocationFromAssetId.ts
index c3deb5c7..31ff6806 100644
--- a/src/createXcmTypes/util/constructForeignAssetMultiLocationFromAssetId.ts
+++ b/src/createXcmTypes/util/constructForeignAssetMultiLocationFromAssetId.ts
@@ -36,8 +36,8 @@ export const constructForeignAssetMultiLocationFromAssetId = (
 	const palletInstanceJunctionStr = `{"PalletInstance":"${foreignAssetsPalletInstance}"},`;
 	const interiorMultiLocationStr = `{${numberOfJunctions}:[${palletInstanceJunctionStr}${junctions}]}`;
 	const multiLocation = {
-		// TODO: keying into any xcm field should be standardized to all caps.
-		parents: assetIdMultiLocation['Parents'] || assetIdMultiLocation['parents'],
+		// Since sanitizeKeys is run in resolveMultiLocation Parents will always be capitalized
+		parents: assetIdMultiLocation['Parents'] as string | number,
 		interior: JSON.parse(interiorMultiLocationStr) as AnyJson,
 	};
 
diff --git a/src/createXcmTypes/util/sortMultiAssetsAscending.ts b/src/createXcmTypes/util/sortMultiAssetsAscending.ts
index cc1188fa..fa1041dd 100644
--- a/src/createXcmTypes/util/sortMultiAssetsAscending.ts
+++ b/src/createXcmTypes/util/sortMultiAssetsAscending.ts
@@ -1,5 +1,7 @@
 // Copyright 2023 Parity Technologies (UK) Ltd.
 
+/* eslint-disable @typescript-eslint/no-non-null-assertion */
+/* eslint-disable no-case-declarations */
 import { stringToHex } from '@polkadot/util';
 import { BN } from 'bn.js';
 
@@ -32,8 +34,8 @@ export const sortMultiAssetsAscending = (multiAssets: FungibleStrMultiAsset[] |
 			);
 		}
 
-		const aParents = a.id.Concrete.parents || a.id.Concrete['Parents'];
-		const bParents = b.id.Concrete.parents || b.id.Concrete['Parents'];
+		const aParents = (a.id.Concrete.parents || a.id.Concrete['Parents']) as string | number;
+		const bParents = (b.id.Concrete.parents || b.id.Concrete['Parents']) as string | number;
 		if (aParents < bParents) {
 			parentSortOrder = -1;
 		} else if (aParents > bParents) {
diff --git a/src/util/getFeeAssetItemIndex.ts b/src/util/getFeeAssetItemIndex.ts
index 6ffc042e..3001d600 100644
--- a/src/util/getFeeAssetItemIndex.ts
+++ b/src/util/getFeeAssetItemIndex.ts
@@ -98,9 +98,9 @@ export const getFeeAssetItemIndex = async (
 
 	if (result === -1) {
 		throw new BaseError(
-			`Invalid paysWithFeeDest value. ${paysWithFeeDest} did not match any asset in assets: ${multiAssets.map((asset) =>
-				JSON.stringify(asset.id.Concrete.interior)
-			)}`,
+			`Invalid paysWithFeeDest value. ${paysWithFeeDest} did not match any asset in assets: ${multiAssets
+				.map((asset) => JSON.stringify(asset.id.Concrete.interior))
+				.join(',')}`,
 			BaseErrorsEnum.InvalidInput
 		);
 	}
diff --git a/src/util/sanitizeKeys.ts b/src/util/sanitizeKeys.ts
index 898ad096..8e4802aa 100644
--- a/src/util/sanitizeKeys.ts
+++ b/src/util/sanitizeKeys.ts
@@ -43,7 +43,7 @@ export const sanitizeKeys = <T extends AnyObj>(xcmObj: T): T => {
 const mapKey = (key: string): string => {
 	const lowerKey = key.toLowerCase();
 	if (MultiLocationJunctionTypeKeys[lowerKey]) {
-		return MultiLocationJunctionTypeKeys[lowerKey];
+		return MultiLocationJunctionTypeKeys[lowerKey] as string;
 	}
 	return key[0].toUpperCase() + key.slice(1).toLowerCase();
 };