diff --git a/packages/api-derive/src/accounts/idToIndex.ts b/packages/api-derive/src/accounts/idToIndex.ts
index 000e0e08eb..84f6470b12 100644
--- a/packages/api-derive/src/accounts/idToIndex.ts
+++ b/packages/api-derive/src/accounts/idToIndex.ts
@@ -27,12 +27,11 @@ import { drr } from '../util/drr';
  */
 export function idToIndex (api: ApiInterfaceRx): (accountId: AccountId | string) => Observable<AccountIndex | undefined> {
   return (accountId: AccountId | string): Observable<AccountIndex | undefined> =>
-    indexes(api)()
-      .pipe(
-        startWith({}),
-        map((indexes: AccountIndexes): AccountIndex | undefined =>
-          (indexes || {})[accountId.toString()]
-        ),
-        drr()
-      );
+    indexes(api)().pipe(
+      startWith({}),
+      map((indexes: AccountIndexes): AccountIndex | undefined =>
+        (indexes || {})[accountId.toString()]
+      ),
+      drr()
+    );
 }
diff --git a/packages/api-derive/src/accounts/indexToId.ts b/packages/api-derive/src/accounts/indexToId.ts
index 5118813bd0..5da8eb6a36 100644
--- a/packages/api-derive/src/accounts/indexToId.ts
+++ b/packages/api-derive/src/accounts/indexToId.ts
@@ -32,7 +32,8 @@ export function indexToId (api: ApiInterfaceRx): (accountIndex: AccountIndex | s
       ? _accountIndex
       : createType('AccountIndex', _accountIndex);
 
-    return (querySection.enumSet<Vec<AccountId>>(accountIndex.div(ENUMSET_SIZE)))
+    return querySection
+      .enumSet<Vec<AccountId>>(accountIndex.div(ENUMSET_SIZE))
       .pipe(
         startWith([]),
         map((accounts): AccountId | undefined =>
diff --git a/packages/api-derive/src/accounts/indexes.ts b/packages/api-derive/src/accounts/indexes.ts
index adbfd87342..a8fb4d095d 100644
--- a/packages/api-derive/src/accounts/indexes.ts
+++ b/packages/api-derive/src/accounts/indexes.ts
@@ -33,7 +33,8 @@ const enumsetSize = ENUMSET_SIZE.toNumber();
  */
 export function indexes (api: ApiInterfaceRx): () => Observable<AccountIndexes> {
   return (): Observable<AccountIndexes> => {
-    return (api.query.indices.nextEnumSet<AccountIndex>())
+    return api.query.indices
+      .nextEnumSet<AccountIndex>()
       .pipe(
         // use the nextEnumSet (which is a counter of the number of sets) to construct
         // a range of values to query [0, 1, 2, ...]. Retrieve the full enum set for the
diff --git a/packages/api-derive/src/imOnline/receivedHeartbeats.ts b/packages/api-derive/src/imOnline/receivedHeartbeats.ts
index 4178d6e5f3..440715842d 100644
--- a/packages/api-derive/src/imOnline/receivedHeartbeats.ts
+++ b/packages/api-derive/src/imOnline/receivedHeartbeats.ts
@@ -3,8 +3,9 @@
 // of the Apache-2.0 license. See the LICENSE file for details.
 
 import { AccountId, SessionIndex } from '@polkadot/types/interfaces';
+import { DerivedHeartbeats } from '../types';
 
-import { of, Observable } from 'rxjs';
+import { of, Observable, combineLatest } from 'rxjs';
 import { map, switchMap } from 'rxjs/operators';
 import { ApiInterfaceRx } from '@polkadot/api/types';
 import { Bytes, Vec } from '@polkadot/types';
@@ -14,25 +15,29 @@ import { drr } from '../util/drr';
 /**
  * @description Return a boolean array indicating whether the passed accounts had received heartbeats in the current session
  */
-export function receivedHeartbeats (api: ApiInterfaceRx): (addresses: (AccountId | string)[]) => Observable<boolean[]> {
-  return (addresses: (AccountId | string)[]): Observable<boolean[]> => {
+export function receivedHeartbeats (api: ApiInterfaceRx): () => Observable<DerivedHeartbeats> {
+  return (): Observable<DerivedHeartbeats> => {
     return api.query.imOnline && api.query.imOnline.receivedHeartbeats
-      ? api.queryMulti<[SessionIndex, Vec<AccountId>]>([
-        api.query.session.currentIndex,
-        api.query.imOnline.keys
+      ? api.queryMulti<[Vec<AccountId>, SessionIndex]>([
+        api.query.imOnline.keys,
+        api.query.session.currentIndex
       ]).pipe(
-        switchMap(([currentIndex, keys]): Observable<Bytes[]> =>
-          api.query.imOnline.receivedHeartbeats.multi(
-            addresses.map((address): [SessionIndex, number] =>
-              [currentIndex, keys.indexOf(address)]
+        switchMap(([keys, currentIndex]): Observable<[AccountId[], Bytes[]]> =>
+          combineLatest([
+            of(keys),
+            api.query.imOnline.receivedHeartbeats.multi<Bytes>(
+              keys.map((_address, index): [SessionIndex, number] => [currentIndex, index])
             )
-          )
+          ])
         ),
-        map((heartbeats): boolean[] =>
-          heartbeats.map((heartbeat): boolean => !heartbeat.isEmpty)
+        map(([keys, heartbeats]): DerivedHeartbeats =>
+          keys.reduce((result: DerivedHeartbeats, key, index): DerivedHeartbeats => ({
+            ...result,
+            [key.toString()]: !!heartbeats[index] && !heartbeats[index].isEmpty
+          }), {})
         ),
         drr()
       )
-      : of([...new Array(addresses.length).keys()].map((): boolean => false));
+      : of({});
   };
 }
diff --git a/packages/api-derive/src/types.ts b/packages/api-derive/src/types.ts
index d27a133f0a..70defb5365 100644
--- a/packages/api-derive/src/types.ts
+++ b/packages/api-derive/src/types.ts
@@ -56,6 +56,8 @@ export interface DerivedFees {
   transferFee: Balance;
 }
 
+export type DerivedHeartbeats = Record<string, boolean>;
+
 export interface RecentlyOffline {
   blockNumber: BlockNumber;
   count: BN;