diff --git a/packages/@aws-cdk/aws-codebuild/lib/project.ts b/packages/@aws-cdk/aws-codebuild/lib/project.ts
index 91feef13f27ce..02b0ed08152d8 100644
--- a/packages/@aws-cdk/aws-codebuild/lib/project.ts
+++ b/packages/@aws-cdk/aws-codebuild/lib/project.ts
@@ -42,7 +42,7 @@ export interface IProject extends IResource, iam.IGrantable, ec2.IConnectable {
    *
    * @see https://docs.aws.amazon.com/codebuild/latest/userguide/sample-build-notifications.html
    */
-  onEvent(id: string, options: events.OnEventOptions): events.Rule;
+  onEvent(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines a CloudWatch event rule triggered when the build project state
@@ -69,7 +69,7 @@ export interface IProject extends IResource, iam.IGrantable, ec2.IConnectable {
    *
    * @see https://docs.aws.amazon.com/codebuild/latest/userguide/sample-build-notifications.html
    */
-  onStateChange(id: string, options: events.OnEventOptions): events.Rule;
+  onStateChange(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines a CloudWatch event rule that triggers upon phase change of this
@@ -77,22 +77,22 @@ export interface IProject extends IResource, iam.IGrantable, ec2.IConnectable {
    *
    * @see https://docs.aws.amazon.com/codebuild/latest/userguide/sample-build-notifications.html
    */
-  onPhaseChange(id: string, options: events.OnEventOptions): events.Rule;
+  onPhaseChange(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines an event rule which triggers when a build starts.
    */
-  onBuildStarted(id: string, options: events.OnEventOptions): events.Rule;
+  onBuildStarted(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines an event rule which triggers when a build fails.
    */
-  onBuildFailed(id: string, options: events.OnEventOptions): events.Rule;
+  onBuildFailed(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines an event rule which triggers when a build completes successfully.
    */
-  onBuildSucceeded(id: string, options: events.OnEventOptions): events.Rule;
+  onBuildSucceeded(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * @returns a CloudWatch metric associated with this build project.
diff --git a/packages/@aws-cdk/aws-config/lib/rule.ts b/packages/@aws-cdk/aws-config/lib/rule.ts
index 8d076e6365b0c..57261c543531c 100644
--- a/packages/@aws-cdk/aws-config/lib/rule.ts
+++ b/packages/@aws-cdk/aws-config/lib/rule.ts
@@ -19,17 +19,17 @@ export interface IRule extends IResource {
    * Defines a CloudWatch event rule which triggers for rule events. Use
    * `rule.addEventPattern(pattern)` to specify a filter.
    */
-  onEvent(id: string, options: events.OnEventOptions): events.Rule;
+  onEvent(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines a CloudWatch event rule which triggers for rule compliance events.
    */
-  onComplianceChange(id: string, options: events.OnEventOptions): events.Rule;
+  onComplianceChange(id: string, options?: events.OnEventOptions): events.Rule;
 
   /**
    * Defines a CloudWatch event rule which triggers for rule re-evaluation status events.
    */
-  onReEvaluationStatus(id: string, options: events.OnEventOptions): events.Rule;
+  onReEvaluationStatus(id: string, options?: events.OnEventOptions): events.Rule;
 }
 
 /**
diff --git a/packages/@aws-cdk/aws-rds/lib/instance.ts b/packages/@aws-cdk/aws-rds/lib/instance.ts
index e542888b2a76a..0574d8150f947 100644
--- a/packages/@aws-cdk/aws-rds/lib/instance.ts
+++ b/packages/@aws-cdk/aws-rds/lib/instance.ts
@@ -53,7 +53,7 @@ export interface IDatabaseInstance extends IResource, ec2.IConnectable, secretsm
    * Defines a CloudWatch event rule which triggers for instance events. Use
    * `rule.addEventPattern(pattern)` to specify a filter.
    */
-  onEvent(id: string, options: events.OnEventOptions): events.Rule;
+  onEvent(id: string, options?: events.OnEventOptions): events.Rule;
 }
 
 /**
diff --git a/packages/@aws-cdk/aws-s3/lib/bucket.ts b/packages/@aws-cdk/aws-s3/lib/bucket.ts
index 2607167c38e05..75d85f2ad3a83 100644
--- a/packages/@aws-cdk/aws-s3/lib/bucket.ts
+++ b/packages/@aws-cdk/aws-s3/lib/bucket.ts
@@ -174,7 +174,7 @@ export interface IBucket extends IResource {
    * @param id The id of the rule
    * @param options Options for adding the rule
    */
-  onCloudTrailEvent(id: string, options: OnCloudTrailBucketEventOptions): events.Rule;
+  onCloudTrailEvent(id: string, options?: OnCloudTrailBucketEventOptions): events.Rule;
 
   /**
    * Defines an AWS CloudWatch event rule that can trigger a target when an image is pushed to this
@@ -186,7 +186,7 @@ export interface IBucket extends IResource {
    * @param id The id of the rule
    * @param options Options for adding the rule
    */
-  onCloudTrailPutObject(id: string, options: OnCloudTrailBucketEventOptions): events.Rule;
+  onCloudTrailPutObject(id: string, options?: OnCloudTrailBucketEventOptions): events.Rule;
 }
 
 /**