diff --git a/.changeset/fluffy-dodos-rule.md b/.changeset/fluffy-dodos-rule.md
new file mode 100644
index 0000000000..7ec2f5bcc8
--- /dev/null
+++ b/.changeset/fluffy-dodos-rule.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/vercel': patch
+---
+
+log only once in serverless adapter
diff --git a/packages/integrations/vercel/src/serverless/adapter.ts b/packages/integrations/vercel/src/serverless/adapter.ts
index 88887fd3a6..de6ddb83ea 100644
--- a/packages/integrations/vercel/src/serverless/adapter.ts
+++ b/packages/integrations/vercel/src/serverless/adapter.ts
@@ -245,6 +245,8 @@ You can set functionPerRoute: false to prevent surpassing the limit.`
 				const filesToInclude = includeFiles?.map((file) => new URL(file, _config.root)) || [];
 				filesToInclude.push(...extraFilesToInclude);
 
+				validateRuntime();
+
 				// Multiple entrypoint support
 				if (_entryPoints.size) {
 					const getRouteFuncName = (route: RouteData) => route.component.replace('src/pages/', '');
@@ -312,7 +314,7 @@ You can set functionPerRoute: false to prevent surpassing the limit.`
 	};
 }
 
-function getRuntime() {
+function validateRuntime() {
 	const version = process.version.slice(1); // 'v16.5.0' --> '16.5.0'
 	const major = version.split('.')[0]; // '16.5.0' --> '16'
 	const support = SUPPORTED_NODE_VERSIONS[major];
@@ -322,7 +324,7 @@ function getRuntime() {
 		);
 		console.warn(`[${PACKAGE_NAME}] Your project will use Node.js 18 as the runtime instead.`);
 		console.warn(`[${PACKAGE_NAME}] Consider switching your local version to 18.`);
-		return 'nodejs18.x';
+		return;
 	}
 	if (support.status === 'deprecated') {
 		console.warn(
@@ -336,5 +338,14 @@ function getRuntime() {
 		);
 		console.warn(`[${PACKAGE_NAME}] Consider upgrading your local version to 18.`);
 	}
+}
+
+function getRuntime() {
+	const version = process.version.slice(1); // 'v16.5.0' --> '16.5.0'
+	const major = version.split('.')[0]; // '16.5.0' --> '16'
+	const support = SUPPORTED_NODE_VERSIONS[major];
+	if (support === undefined) {
+		return 'nodejs18.x';
+	}
 	return `nodejs${major}.x`;
 }