diff --git a/packages/@aws-cdk/aws-rds/README.md b/packages/@aws-cdk/aws-rds/README.md
index 18d61eb54cc00..f65bb45fd63db 100644
--- a/packages/@aws-cdk/aws-rds/README.md
+++ b/packages/@aws-cdk/aws-rds/README.md
@@ -70,7 +70,7 @@ const instance = new rds.DatabaseInstance(this, 'Instance', {
   engine: rds.DatabaseInstanceEngine.oracleSe2({ version: rds.OracleEngineVersion.VER_19_0_0_0_2020_04_R1 }),
   // optional, defaults to m5.large
   instanceType: ec2.InstanceType.of(ec2.InstanceClass.BURSTABLE3, ec2.InstanceSize.SMALL),
-  masterUsername: rds.Credentials.fromUsername('syscdk'), // Optional - will default to admin
+  credentials: rds.Credentials.fromUsername('syscdk'), // Optional - will default to admin
   vpc,
   vpcSubnets: {
     subnetType: ec2.SubnetType.PRIVATE