diff --git a/.changeset/early-pigs-boil.md b/.changeset/early-pigs-boil.md
new file mode 100644
index 000000000000..ed80cc0dcf0d
--- /dev/null
+++ b/.changeset/early-pigs-boil.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: create separate functions for ISR routes
diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 06c3cbbed9e8..60851cc6bd47 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -358,7 +358,8 @@ function hash_config(config) {
 		config.external ?? '',
 		config.regions ?? '',
 		config.memory ?? '',
-		config.maxDuration ?? ''
+		config.maxDuration ?? '',
+		!!config.isr // need to distinguish ISR from non-ISR functions, because ISR functions can't use streaming mode
 	].join('/');
 }