diff --git a/src/beacon-api-client.js b/src/beacon-api-client.js
index b7d1d51..bb187d7 100644
--- a/src/beacon-api-client.js
+++ b/src/beacon-api-client.js
@@ -1,4 +1,5 @@
 import axios from 'axios';
+import qs from 'qs';
 
 class BeaconAPIClient {
   constructor(beaconAPIs) {
@@ -9,13 +10,20 @@ class BeaconAPIClient {
   }
 
   async getValidators(stateId, pubKeys) {
-    const { data } = await this.queryEndpoint(`/eth/v1/beacon/states/${stateId}/validators?id=${pubKeys.join(',')}`)
+    const options = {
+      params: { id: pubKeys },
+      paramsSerializer: (params) => {
+        return qs.stringify(params, { arrayFormat: 'repeat' })
+      }
+    };
+
+    const { data } = await this.queryEndpoint(`/eth/v1/beacon/states/${stateId}/validators`, options)
     return data;
   }
 
-  async queryEndpoint(url) {
+  async queryEndpoint(url, options = {}) {
     try {
-      const data = await this.http.get(url)
+      const data = await this.http.get(url, options)
       return data
     } catch (err) {
       console.log(`Request to ${url} failed with error ${err.message}`)
diff --git a/src/utils.js b/src/utils.js
index e32ab34..9a71af0 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -1 +1,23 @@
-export const validatorShortName = (pubkey) => pubkey.slice(2,9);
+export const validatorShortName = (pubkey) => pubkey.slice(2, 9);
+
+const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms))
+
+export async function withRetry(fn, options = {}) {
+  const { maxAttempts = 5, interval = 3000 } = options;
+  let attempts = 0;
+
+  while (attempts < maxAttempts) {
+    try {
+      return await fn();
+    } catch (err) {
+      attempts++;
+      console.warn(`${attempts} of ${maxAttempts} attempts failed with error: ${err}`);
+
+      if (attempts == maxAttempts) {
+        throw new Error(`Failed after ${attempts} attempts: ${err}`);
+      }
+
+      await sleep(interval);
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/validator-polling-service.js b/src/validator-polling-service.js
index 3f02d49..e89cef5 100644
--- a/src/validator-polling-service.js
+++ b/src/validator-polling-service.js
@@ -3,7 +3,7 @@ const SECONDS_PER_SLOT = 12;
 const SLOTS_PER_EPOCH = 32;
 const SECONDS_PER_EPOCH = SECONDS_PER_SLOT * SLOTS_PER_EPOCH;
 
-import { validatorShortName } from './utils.js';
+import { validatorShortName, withRetry } from './utils.js';
 
 class ValidatorPollingService {
   #pollingIntervalSeconds;
@@ -31,7 +31,7 @@ class ValidatorPollingService {
     if (!allValid) throw new Error(`Failed to add validator key(s)`)
 
     this.#validatorPubKeys = this.#validatorPubKeys.concat(newPubKeys);
-    
+
     console.log(`Validator(s) added: ${newPubKeys.map(k => validatorShortName(k)).join(',')}`)
   }
 
@@ -67,13 +67,17 @@ class ValidatorPollingService {
       this.#genesisTime = await this.#beaconApiClient.getGenesisTime();
     }
 
-    const currentSlot = Math.floor((new Date().getTime() / 1000 - this.#genesisTime) / SECONDS_PER_SLOT);
-    const previousEpochSlot = currentSlot - SLOTS_PER_EPOCH;
+    const queryValidatorStates = () => {
+      const currentSlot = Math.floor((new Date().getTime() / 1000 - this.#genesisTime) / SECONDS_PER_SLOT) - 1;
+      const previousEpochSlot = currentSlot - SLOTS_PER_EPOCH;
+
+      return Promise.all([
+        this.#beaconApiClient.getValidators(currentSlot, this.#validatorPubKeys),
+        this.#beaconApiClient.getValidators(previousEpochSlot, this.#validatorPubKeys),
+      ]);
+    };
 
-    const [currentEpochData, previousEpochData] = await Promise.all([
-      this.#beaconApiClient.getValidators(currentSlot, this.#validatorPubKeys),
-      this.#beaconApiClient.getValidators(previousEpochSlot, this.#validatorPubKeys),
-    ]);
+    const [currentEpochData, previousEpochData] = await withRetry(queryValidatorStates, { interval: SECONDS_PER_EPOCH });
 
     const validatorStates = mergeValidatorData(currentEpochData.data, previousEpochData.data)
     this.#listeners.forEach(listener => listener(validatorStates));