diff --git a/build.gradle b/build.gradle
index 40819857..33e81ff2 100644
--- a/build.gradle
+++ b/build.gradle
@@ -450,6 +450,7 @@ int endJmxPort = startJmxPort
 integTest {
     useCluster testClusters.leaderCluster
     useCluster testClusters.followCluster
+    systemProperty "password", "admin" // setting it to `admin` explicitly since its a custom security setup
 
     if(knnEnabled){
         nonInputProperties.systemProperty('tests.knn_plugin_enabled', "true")
diff --git a/src/test/kotlin/org/opensearch/replication/MultiClusterRestTestCase.kt b/src/test/kotlin/org/opensearch/replication/MultiClusterRestTestCase.kt
index 84b73b85..185cadc4 100644
--- a/src/test/kotlin/org/opensearch/replication/MultiClusterRestTestCase.kt
+++ b/src/test/kotlin/org/opensearch/replication/MultiClusterRestTestCase.kt
@@ -236,9 +236,9 @@ abstract class MultiClusterRestTestCase : OpenSearchTestCase() {
                 defaultHeaders[i++] = BasicHeader(key, value)
             }
 
-            val creds = System.getProperty("user", "admin") + System.getProperty("password", "myStrongPassword123!");
+            val creds = System.getProperty("user", "admin") + ":" + System.getProperty("password", "myStrongPassword123!")
             if(securityEnabled) {
-                defaultHeaders[i++] = BasicHeader("Authorization", "Basic " + Base64.getUrlEncoder().encodeToString(creds.toByteArray(StandardCharsets.UTF_8)))
+                defaultHeaders[i++] = BasicHeader("Authorization", "Basic " + Base64.getEncoder().encodeToString(creds.toByteArray(StandardCharsets.UTF_8)))
             }
 
             builder.setDefaultHeaders(defaultHeaders)