diff --git a/types/eventsource/eventsource-tests.ts b/types/eventsource/eventsource-tests.ts
index c1b53030cd..d06c79cdde 100644
--- a/types/eventsource/eventsource-tests.ts
+++ b/types/eventsource/eventsource-tests.ts
@@ -10,9 +10,9 @@ let openState: number = eventSource.OPEN;
 openState = EventSource.OPEN;
 let url: string = eventSource.url;
 let withCredentials: boolean = eventSource.withCredentials;
-eventSource.onmessage = (event: Event) => {};
-eventSource.onerror = (event: Event) => {};
-eventSource.onopen = (event: Event) => {};
+eventSource.onmessage = (event: MessageEvent) => {};
+eventSource.onerror = (event: MessageEvent) => {};
+eventSource.onopen = (event: MessageEvent) => {};
 eventSource.addEventListener = (type: string, listener: (e: Event) => void) => {};
 eventSource.dispatchEvent = (event: Event) => true;
 eventSource.removeEventListener = (type: string, listener: (e: Event) => void) => {};
@@ -30,9 +30,9 @@ openState = eventSource.OPEN;
 openState = EventSource.OPEN;
 url = eventSourcePolyfill.url;
 withCredentials = eventSource.withCredentials;
-eventSourcePolyfill.onmessage = (event: Event) => {};
-eventSourcePolyfill.onerror = (event: Event) => {};
-eventSourcePolyfill.onopen = (event: Event) => {};
+eventSourcePolyfill.onmessage = (event: MessageEvent) => {};
+eventSourcePolyfill.onerror = (event: MessageEvent) => {};
+eventSourcePolyfill.onopen = (event: MessageEvent) => {};
 eventSourcePolyfill.addEventListener = (type: string, listener: (e: Event) => void) => {};
 eventSourcePolyfill.dispatchEvent = (event: Event) => true;
 eventSourcePolyfill.removeEventListener = (type: string, listener: (e: Event) => void) => {};