diff --git a/e2e-tests/historical/endpoints/kusama/runtime/spec/10000.json b/e2e-tests/historical/endpoints/kusama/runtime/spec/10000.json
index 734874ad4..09f46300f 100644
--- a/e2e-tests/historical/endpoints/kusama/runtime/spec/10000.json
+++ b/e2e-tests/historical/endpoints/kusama/runtime/spec/10000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "2",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/kusama/runtime/spec/100000.json b/e2e-tests/historical/endpoints/kusama/runtime/spec/100000.json
index 6ef40674b..60c9f807d 100644
--- a/e2e-tests/historical/endpoints/kusama/runtime/spec/100000.json
+++ b/e2e-tests/historical/endpoints/kusama/runtime/spec/100000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "2",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/kusama/runtime/spec/2000000.json b/e2e-tests/historical/endpoints/kusama/runtime/spec/2000000.json
index 3dc9c2b56..f7394828e 100644
--- a/e2e-tests/historical/endpoints/kusama/runtime/spec/2000000.json
+++ b/e2e-tests/historical/endpoints/kusama/runtime/spec/2000000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "2",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/kusama/runtime/spec/4000000.json b/e2e-tests/historical/endpoints/kusama/runtime/spec/4000000.json
index 9ad04a885..72b953572 100644
--- a/e2e-tests/historical/endpoints/kusama/runtime/spec/4000000.json
+++ b/e2e-tests/historical/endpoints/kusama/runtime/spec/4000000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "2",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/kusama/runtime/spec/8000000.json b/e2e-tests/historical/endpoints/kusama/runtime/spec/8000000.json
index 6b167d69c..83b183503 100644
--- a/e2e-tests/historical/endpoints/kusama/runtime/spec/8000000.json
+++ b/e2e-tests/historical/endpoints/kusama/runtime/spec/8000000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "2",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/polkadot/runtime/spec/1000.json b/e2e-tests/historical/endpoints/polkadot/runtime/spec/1000.json
index e46056c60..517e9c95e 100644
--- a/e2e-tests/historical/endpoints/polkadot/runtime/spec/1000.json
+++ b/e2e-tests/historical/endpoints/polkadot/runtime/spec/1000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "0",
         "tokenDecimals": [
             "10"
diff --git a/e2e-tests/historical/endpoints/polkadot/runtime/spec/200000.json b/e2e-tests/historical/endpoints/polkadot/runtime/spec/200000.json
index 5c9eb041a..0bbe560d1 100644
--- a/e2e-tests/historical/endpoints/polkadot/runtime/spec/200000.json
+++ b/e2e-tests/historical/endpoints/polkadot/runtime/spec/200000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "0",
         "tokenDecimals": [
             "10"
diff --git a/e2e-tests/historical/endpoints/polkadot/runtime/spec/3000000.json b/e2e-tests/historical/endpoints/polkadot/runtime/spec/3000000.json
index 613b9fc97..0d63aeb96 100644
--- a/e2e-tests/historical/endpoints/polkadot/runtime/spec/3000000.json
+++ b/e2e-tests/historical/endpoints/polkadot/runtime/spec/3000000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "0",
         "tokenDecimals": [
             "10"
diff --git a/e2e-tests/historical/endpoints/polkadot/runtime/spec/6877002.json b/e2e-tests/historical/endpoints/polkadot/runtime/spec/6877002.json
index fc7c1a4d8..518927abd 100644
--- a/e2e-tests/historical/endpoints/polkadot/runtime/spec/6877002.json
+++ b/e2e-tests/historical/endpoints/polkadot/runtime/spec/6877002.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "0",
         "tokenDecimals": [
             "10"
diff --git a/e2e-tests/historical/endpoints/westend/runtime/spec/10000.json b/e2e-tests/historical/endpoints/westend/runtime/spec/10000.json
index 5a5114119..cc9d9e435 100644
--- a/e2e-tests/historical/endpoints/westend/runtime/spec/10000.json
+++ b/e2e-tests/historical/endpoints/westend/runtime/spec/10000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "42",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/westend/runtime/spec/2000000.json b/e2e-tests/historical/endpoints/westend/runtime/spec/2000000.json
index f69e29b48..b0bbdc86a 100644
--- a/e2e-tests/historical/endpoints/westend/runtime/spec/2000000.json
+++ b/e2e-tests/historical/endpoints/westend/runtime/spec/2000000.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "42",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/historical/endpoints/westend/runtime/spec/7417678.json b/e2e-tests/historical/endpoints/westend/runtime/spec/7417678.json
index 4bbb2987f..b8ec43e2a 100644
--- a/e2e-tests/historical/endpoints/westend/runtime/spec/7417678.json
+++ b/e2e-tests/historical/endpoints/westend/runtime/spec/7417678.json
@@ -12,6 +12,7 @@
         "live": null
     },
     "properties": {
+        "isEthereum": false,
         "ss58Format": "42",
         "tokenDecimals": [
             "12"
diff --git a/e2e-tests/jest.config.js b/e2e-tests/jest.config.js
index c295b03d7..c729b162a 100644
--- a/e2e-tests/jest.config.js
+++ b/e2e-tests/jest.config.js
@@ -6,9 +6,14 @@ module.exports = {
     testEnvironment: 'node',
 	maxConcurrency: 3,
 	maxWorkers: '50%',
-    globals: {
-        'ts-jest': {
-            isloatedModules: true
-        }
-    }
+    transform: {
+        // '^.+\\.[tj]sx?$' to process js/ts with `ts-jest`
+        // '^.+\\.m?[tj]sx?$' to process js/ts/mjs/mts with `ts-jest`
+        '^.+\\.tsx?$': [
+          'ts-jest',
+          {
+            isolatedModules: true
+          },
+        ],
+    },
 };
diff --git a/src/sanitize/sanitizeNumbers.ts b/src/sanitize/sanitizeNumbers.ts
index c7f4f33cd..9677fb3d1 100644
--- a/src/sanitize/sanitizeNumbers.ts
+++ b/src/sanitize/sanitizeNumbers.ts
@@ -236,7 +236,10 @@ function mapTypeSanitizeKeyValue(
 	const jsonMap: AnyJson = {};
 
 	map.forEach((value: unknown, key: unknown) => {
-		const nonCodecKey = sanitizeNumbers(key, options);
+		let nonCodecKey = sanitizeNumbers(key, options);
+		if (typeof nonCodecKey === 'object') {
+			nonCodecKey = JSON.stringify(nonCodecKey);
+		}
 		if (!(typeof nonCodecKey === 'string' || typeof nonCodecKey === 'number')) {
 			throw new InternalServerError(
 				'Unexpected non-string and non-number key while sanitizing a Map-like type'