diff --git a/package.json b/package.json
index a6c50fd0..4452de68 100644
--- a/package.json
+++ b/package.json
@@ -35,7 +35,6 @@
   },
   "devDependencies": {
     "@sinonjs/fake-timers": "14.0.0",
-    "@types/eventsource": "1.1.15",
     "@types/node": "22.10.2",
     "@types/sinonjs__fake-timers": "8.1.5",
     "@types/ws": "8.5.13",
diff --git a/src/adapter/types.ts b/src/adapter/types.ts
index ad2971d2..1bde1959 100644
--- a/src/adapter/types.ts
+++ b/src/adapter/types.ts
@@ -1,4 +1,4 @@
-import type EventSource from 'eventsource'
+import { EventSource } from 'eventsource'
 import Redis from 'ioredis'
 import { Cache } from '../cache'
 import { AdapterConfig, BaseAdapterSettings, SettingsDefinitionMap } from '../config'
diff --git a/src/transports/sse.ts b/src/transports/sse.ts
index ffcea000..c8861ee3 100644
--- a/src/transports/sse.ts
+++ b/src/transports/sse.ts
@@ -1,5 +1,5 @@
 import { AxiosRequestConfig } from 'axios'
-import EventSource from 'eventsource'
+import { EventSource } from 'eventsource'
 import { EndpointContext } from '../adapter'
 import { calculateHttpRequestKey } from '../cache'
 import { makeLogger, sleep } from '../util'
@@ -13,7 +13,7 @@ const logger = makeLogger('SSETransport')
 
 export interface SSEConfig {
   url: string
-  eventSourceInitDict?: EventSource.EventSourceInitDict
+  headers?: Record<string, string>
 }
 
 /**
@@ -103,7 +103,13 @@ export class SseTransport<T extends SSETransportGenerics> extends StreamingTrans
       logger.debug('No established connection and new subscriptions available, connecting to SSE')
       const sseConfig = this.config.prepareSSEConnectionConfig(subscriptions.new, context)
       this.providerDataStreamEstablished = Date.now()
-      this.sseConnection = new this.EventSource(sseConfig.url, sseConfig.eventSourceInitDict)
+      this.sseConnection = new this.EventSource(sseConfig.url, {
+        fetch: (input, init) =>
+          fetch(input, {
+            ...init,
+            headers: { ...init?.headers, ...sseConfig.headers },
+          }),
+      })
 
       const eventHandlerGenerator = (listener: (typeof this.config.eventListeners)[0]) => {
         return (e: MessageEvent) => {
diff --git a/tsconfig.json b/tsconfig.json
index 53a4c043..958d757e 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -20,7 +20,8 @@
     "noImplicitThis": true,
     "noPropertyAccessFromIndexSignature": true,
     "noUnusedLocals": true,
-    "strict": true
+    "strict": true,
+    "skipLibCheck": true
   },
   "exclude": ["src/**/test/**/*"],
   "include": ["./src/**/*"]
diff --git a/yarn.lock b/yarn.lock
index c8693357..c8d8bb05 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -326,11 +326,6 @@
   resolved "https://registry.npmjs.org/@types/estree/-/estree-1.0.6.tgz"
   integrity sha512-AYnb1nQyY49te+VRAVgmzfcgjYS91mY5P0TKUDCLEM+gNnA+3T6rWITXRLYCpahpqSQbN5cE+gHpnPyXjHWxcw==
 
-"@types/eventsource@1.1.15":
-  version "1.1.15"
-  resolved "https://registry.npmjs.org/@types/eventsource/-/eventsource-1.1.15.tgz"
-  integrity sha512-XQmGcbnxUNa06HR3VBVkc9+A2Vpi9ZyLJcdS5dwaQQ/4ZMWFO+5c90FnMUpbtMZwB/FChoYHwuVg8TvkECacTA==
-
 "@types/hast@^3.0.4":
   version "3.0.4"
   resolved "https://registry.npmjs.org/@types/hast/-/hast-3.0.4.tgz"