diff --git a/packages/next/src/client/components/router-reducer/fetch-server-response.ts b/packages/next/src/client/components/router-reducer/fetch-server-response.ts
index 3e0034ff935fc..d98698a16da19 100644
--- a/packages/next/src/client/components/router-reducer/fetch-server-response.ts
+++ b/packages/next/src/client/components/router-reducer/fetch-server-response.ts
@@ -178,7 +178,7 @@ export async function fetchServerResponse(
     const interception = !!res.headers.get('vary')?.includes(NEXT_URL)
     const isPrerender = !!res.headers.get(NEXT_IS_PRERENDER_HEADER)
     const postponed = !!res.headers.get(NEXT_DID_POSTPONE_HEADER)
-    let isFlightResponse = contentType === RSC_CONTENT_TYPE_HEADER
+    let isFlightResponse = contentType.startsWith(RSC_CONTENT_TYPE_HEADER)
 
     if (process.env.NODE_ENV === 'production') {
       if (process.env.__NEXT_CONFIG_OUTPUT === 'export') {
diff --git a/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts b/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts
index 9b49a5f6ee51f..a65adaf756efc 100644
--- a/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts
+++ b/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts
@@ -113,7 +113,7 @@ async function fetchServerAction(
 
   const contentType = res.headers.get('content-type')
 
-  if (contentType === RSC_CONTENT_TYPE_HEADER) {
+  if (contentType?.startsWith(RSC_CONTENT_TYPE_HEADER)) {
     const response: ActionFlightResponse = await createFromFetch(
       Promise.resolve(res),
       {
diff --git a/packages/next/src/server/app-render/action-handler.ts b/packages/next/src/server/app-render/action-handler.ts
index ee2b44021976d..6c1bffa84dd56 100644
--- a/packages/next/src/server/app-render/action-handler.ts
+++ b/packages/next/src/server/app-render/action-handler.ts
@@ -218,7 +218,9 @@ async function createForwardedActionResponse(
       },
     })
 
-    if (response.headers.get('content-type') === RSC_CONTENT_TYPE_HEADER) {
+    if (
+      response.headers.get('content-type')?.startsWith(RSC_CONTENT_TYPE_HEADER)
+    ) {
       // copy the headers from the redirect response to the response we're sending
       for (const [key, value] of response.headers) {
         if (!actionsForbiddenHeaders.includes(key)) {
@@ -340,7 +342,11 @@ async function createRedirectRenderResult(
         },
       })
 
-      if (response.headers.get('content-type') === RSC_CONTENT_TYPE_HEADER) {
+      if (
+        response.headers
+          .get('content-type')
+          ?.startsWith(RSC_CONTENT_TYPE_HEADER)
+      ) {
         // copy the headers from the redirect response to the response we're sending
         for (const [key, value] of response.headers) {
           if (!actionsForbiddenHeaders.includes(key)) {