diff --git a/packages/@aws-cdk/aws-rds/lib/instance-parameter-group.ts b/packages/@aws-cdk/aws-rds/lib/instance-parameter-group.ts
index 25c4f037e1489..e59ee6f9aad4d 100644
--- a/packages/@aws-cdk/aws-rds/lib/instance-parameter-group.ts
+++ b/packages/@aws-cdk/aws-rds/lib/instance-parameter-group.ts
@@ -41,7 +41,7 @@ export interface InstanceParameterGroupProps {
   /**
    * The parameters in this parameter group
    */
-  parameters?: Parameters;
+  parameters: Parameters;
 }
 
 /**
diff --git a/packages/@aws-cdk/aws-rds/test/test.cluster.ts b/packages/@aws-cdk/aws-rds/test/test.cluster.ts
index c3829bb57a144..d180173124d58 100644
--- a/packages/@aws-cdk/aws-rds/test/test.cluster.ts
+++ b/packages/@aws-cdk/aws-rds/test/test.cluster.ts
@@ -169,6 +169,7 @@ export = {
     const instanceParameterGroup = new InstanceParameterGroup(stack, 'Params', {
       family: 'mysql',
       description: 'bye',
+      parameters: {},
     });
     instanceParameterGroup.setParameter('param1', 'value1');
     instanceParameterGroup.setParameter('param2', 'value2');
@@ -220,7 +221,8 @@ export = {
     const stack = testStack();
     const group = new InstanceParameterGroup(stack, 'Params', {
       family: 'hello',
-      description: 'desc'
+      description: 'desc',
+      parameters: {},
     });
 
     // WHEN