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) => {};
diff --git a/types/eventsource/index.d.ts b/types/eventsource/index.d.ts
index 1308515917..f0dcd7513f 100644
--- a/types/eventsource/index.d.ts
+++ b/types/eventsource/index.d.ts
@@ -1,7 +1,8 @@
-// Type definitions for eventsource 1.0
+// Type definitions for eventsource 1.1
 // Project: http://github.com/EventSource/eventsource
 // Definitions by: Scott Lee Davis <https://github.com/scottleedavis>
 //                 Ali Afroozeh <https://github.com/afroozeh>
+//                 Pedro Gámez <https://github.com/snakedrak>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
 
@@ -18,9 +19,9 @@ declare class EventSource {
   readonly url: string;
   readonly readyState: number;
   readonly withCredentials: boolean;
-  onopen: EventListener;
-  onmessage: EventListener;
-  onerror: EventListener;
+  onopen: (evt: MessageEvent) => any;
+  onmessage: (evt: MessageEvent) => any;
+  onerror: (evt: MessageEvent) => any;
   addEventListener(type: string, listener: EventListener): void;
   dispatchEvent(evt: Event): boolean;
   removeEventListener(type: string, listener?: EventListener): void;
@@ -28,7 +29,7 @@ declare class EventSource {
 }
 
 declare namespace EventSource {
-  enum ReadyState {CONNECTING = 0, OPEN = 1, CLOSED = 2}
+  enum ReadyState { CONNECTING = 0, OPEN = 1, CLOSED = 2 }
 
   interface EventSourceInitDict {
     withCredentials?: boolean;
diff --git a/types/eventsource/lib/eventsource-polyfill/index.d.ts b/types/eventsource/lib/eventsource-polyfill/index.d.ts
index 86b82105cc..74e3e22faa 100644
--- a/types/eventsource/lib/eventsource-polyfill/index.d.ts
+++ b/types/eventsource/lib/eventsource-polyfill/index.d.ts
@@ -11,9 +11,9 @@ declare class EventSource {
   readonly url: string;
   readonly readyState: number;
   readonly withCredentials: boolean;
-  onopen: EventListener;
-  onmessage: EventListener;
-  onerror: EventListener;
+  onopen: (evt: MessageEvent) => any;
+  onmessage: (evt: MessageEvent) => any;
+  onerror: (evt: MessageEvent) => any;
   addEventListener(type: string, listener: EventListener): void;
   dispatchEvent(evt: Event): boolean;
   removeEventListener(type: string, listener?: EventListener): void;