diff --git a/src/cloudevents.ts b/src/cloudevents.ts
index 1b9eaa2f..1d28fbe3 100644
--- a/src/cloudevents.ts
+++ b/src/cloudevents.ts
@@ -47,7 +47,9 @@ export function getBinaryCloudEventContext(
   const context: CloudEventsContext = {};
   for (const name in req.headers) {
     if (name.startsWith('ce-')) {
-      const attributeName = name.substr('ce-'.length);
+      const attributeName = name.substr(
+        'ce-'.length
+      ) as keyof CloudEventsContext;
       context[attributeName] = req.header(name);
     }
   }
diff --git a/src/functions.ts b/src/functions.ts
index 91f4f6d9..bedf5505 100644
--- a/src/functions.ts
+++ b/src/functions.ts
@@ -40,6 +40,19 @@ export type HandlerFunction =
   | CloudEventFunction
   | CloudEventFunctionWithCallback;
 
+/**
+ * A legacy event.
+ */
+export interface LegacyEvent {
+  data: object;
+  context: CloudFunctionsContext;
+}
+
+interface Data {
+  data: object;
+}
+export type LegacyCloudFunctionsContext = CloudFunctionsContext | Data;
+
 /**
  * The Cloud Functions context object for the event.
  *
@@ -62,7 +75,7 @@ export interface CloudFunctionsContext {
   /**
    * The resource that emitted the event.
    */
-  resource?: string;
+  resource?: string | object;
 }
 
 /**
@@ -91,17 +104,28 @@ export interface CloudEventsContext {
    * Timestamp of when the event happened.
    */
   time?: string;
+  /**
+   * Describes the subject of the event in the context of the event producer.
+   */
+  subject?: string;
   /**
    * A link to the schema that the event data adheres to.
    */
-  schemaurl?: string;
+  dataschema?: string;
   /**
    * Content type of the event data.
    */
-  contenttype?: string;
-
-  // CloudEvents extension attributes.
-  [key: string]: any;
+  datacontenttype?: string;
+  /**
+   * The event data.
+   */
+  data?:
+    | Record<string, unknown | string | number | boolean>
+    | string
+    | number
+    | boolean
+    | null
+    | unknown;
 }
 
 export type Context = CloudFunctionsContext | CloudEventsContext;