diff --git a/src/eventsource.spec.ts b/src/eventsource.spec.ts
index da79f3c..7da23da 100644
--- a/src/eventsource.spec.ts
+++ b/src/eventsource.spec.ts
@@ -45,7 +45,7 @@ describe('EventSource', () => {
     ev.onopen = () => done();
   });
 
-  it('allows for a custom fetch implementation to be used', (done) => {
+  it('allows for a custom fetch implementation to be via extraOptions used', (done) => {
     mockChunks();
 
     const fetchFn = jest.fn((input, init?) => {
@@ -58,7 +58,29 @@ describe('EventSource', () => {
         disableRetry: true,
       },
       {
-        inputFetch: fetchFn,
+        fetchInput: fetchFn,
+      },
+    );
+
+    ev.onopen = (event) => {
+      expect(event).toBeInstanceOf(Event);
+      expect(fetchFn).toHaveBeenCalled();
+      done();
+    };
+  });
+
+  it('allows for a custom fetch implementation to be via extraOptions used', (done) => {
+    mockChunks();
+
+    const fetchFn = jest.fn((input, init?) => {
+      return globalThis.fetch(input, init);
+    }) as typeof fetch;
+
+    const ev = new EventSource(
+      'http://localhost/sse',
+      {
+        disableRetry: true,
+        fetch: fetchFn,
       },
     );
 
diff --git a/src/eventsource.ts b/src/eventsource.ts
index 0dc0ff6..6a5fef8 100644
--- a/src/eventsource.ts
+++ b/src/eventsource.ts
@@ -4,12 +4,42 @@ import { EventSourceMessage, getLines, getMessages, readChunks } from './parse';
 const ContentTypeEventStream = 'text/event-stream';
 
 export type EventSourceOptions = {
+  /**
+   * Disables connection retrying.
+   */
   disableRetry?: boolean;
+
+  /**
+   * Delay in milliseconds for retrying connection.
+   */
   retry?: number;
+
+  /**
+   * Disables logging.
+   */
   disableLogger?: boolean;
+
+  /**
+   * Logger to use for events and errors. Defaults to console.
+   */
   logger?: Logger;
+
+  /**
+   * Fetch implementation to use for connecting. Defaults to globalThis.fetch
+   */
+  fetch?: typeof fetch;
 } & Omit<RequestInit, 'cache' | 'credentials' | 'signal'>;
 
+/**
+ * @deprecated
+ */
+export type EventSourceExtraOptions = {
+  /**
+   * @deprecated Use {@link EventSourceOptions#fetch} instead
+   */
+  fetchInput?: typeof fetch;
+};
+
 export class CustomEventSource extends EventTarget implements EventSource {
   // https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource-url
   public url: string;
@@ -33,6 +63,7 @@ export class CustomEventSource extends EventTarget implements EventSource {
     | null = null;
 
   public readonly options: EventSourceInit & EventSourceOptions;
+  private readonly extraOptions?: EventSourceExtraOptions;
   private abortController?: AbortController;
   private timeoutId: ReturnType<typeof setTimeout> | undefined = undefined;
   private retry: number;
@@ -40,17 +71,18 @@ export class CustomEventSource extends EventTarget implements EventSource {
 
   private logger?: Logger;
 
-  private fetch: typeof fetch;
-
   constructor(
     url: string | URL,
     initDict?: EventSourceInit & EventSourceOptions,
-    { inputFetch } = { inputFetch: globalThis.fetch.bind(globalThis) },
+    /**
+     * @deprecated Use the related options in initDict
+     */
+    extraOptions?: EventSourceExtraOptions,
   ) {
     super();
-    this.fetch = inputFetch;
-    this.url = url instanceof URL ? url.toString() : url;
     this.options = initDict ?? {};
+    this.extraOptions = extraOptions;
+    this.url = url instanceof URL ? url.toString() : url;
     this.retry = initDict?.retry ?? 5000;
 
     if (!this.options.disableLogger) {
@@ -99,7 +131,11 @@ export class CustomEventSource extends EventTarget implements EventSource {
         signal: this.abortController?.signal,
       };
 
-      const response = await this.fetch(this.url, fetchOptions);
+      const response = this.options.fetch
+        ? await this.options.fetch(this.url, fetchOptions)
+        : this.extraOptions?.fetchInput
+        ? await this.extraOptions.fetchInput(this.url, fetchOptions)
+        : await globalThis.fetch(this.url, fetchOptions);
 
       // https://html.spec.whatwg.org/multipage/server-sent-events.html#dom-eventsource (Step 15)
       if (response.status !== 200) {