diff --git a/packages/node/src/adapter.ts b/packages/node/src/adapter.ts
index 9991fd8..e0b5f35 100644
--- a/packages/node/src/adapter.ts
+++ b/packages/node/src/adapter.ts
@@ -120,10 +120,12 @@ export const adapter: LylaAdapter<LylaAdapterMeta> = ({
       protocol: parsedUrl.protocol
     },
     (incomingMessage) => {
-      onHeadersReceived(
-        ensureResponseHeaders(incomingMessage.headers),
-        clientRequest
-      )
+      if (onHeadersReceived) {
+        onHeadersReceived(
+          ensureResponseHeaders(incomingMessage.headers),
+          clientRequest
+        )
+      }
       const rawResponseContentLength = incomingMessage.headers['content-length']
       const responseContentLength =
         typeof rawResponseContentLength === 'string' &&
diff --git a/packages/universal/src/instance.ts b/packages/universal/src/instance.ts
index 738293d..4d56279 100644
--- a/packages/universal/src/instance.ts
+++ b/packages/universal/src/instance.ts
@@ -41,7 +41,7 @@ export const { lyla, isLylaError } = coreCreateLyla<undefined, LylaAdapterMeta>(
         withCredentials,
         extraOptions,
         onHeadersReceived(headers, originalRequest) {
-          return onHeadersReceived(headers, {
+          return onHeadersReceived?.(headers, {
             anyhow: originalRequest,
             node: originalRequest,
             web: undefined
@@ -118,7 +118,7 @@ export const { lyla, isLylaError } = coreCreateLyla<undefined, LylaAdapterMeta>(
         withCredentials,
         extraOptions,
         onHeadersReceived(headers, originalRequest) {
-          return onHeadersReceived(headers, {
+          return onHeadersReceived?.(headers, {
             anyhow: originalRequest,
             node: undefined,
             web: originalRequest
diff --git a/packages/web/src/adapter.ts b/packages/web/src/adapter.ts
index 6cfe171..4b331bf 100644
--- a/packages/web/src/adapter.ts
+++ b/packages/web/src/adapter.ts
@@ -123,7 +123,9 @@ export const adapter: LylaAdapter<LylaAdapterMeta> = ({
   })
   const _onHeadersReceived = () => {
     if (xhr.readyState === xhr.HEADERS_RECEIVED) {
-      onHeadersReceived(ensureResponseHeaders(), xhr)
+      if (onHeadersReceived) {
+        onHeadersReceived(ensureResponseHeaders(), xhr)
+      }
     }
     xhr.removeEventListener('readystatechange', _onHeadersReceived)
   }