diff --git a/packages/vite/src/node/server/middlewares/transform.ts b/packages/vite/src/node/server/middlewares/transform.ts
index 7b0fb6b1d97979..5c7ec55bd8fb55 100644
--- a/packages/vite/src/node/server/middlewares/transform.ts
+++ b/packages/vite/src/node/server/middlewares/transform.ts
@@ -205,12 +205,14 @@ export function transformMiddleware(
           const type = isDirectCSSRequest(url) ? 'css' : 'js'
           const isDep =
             DEP_VERSION_RE.test(url) || depsOptimizer?.isOptimizedDepUrl(url)
-          const filepath =
-            result.map == null
-              ? (await server.moduleGraph.getModuleByUrl(url, false))?.file
-              : undefined
-          const originalContent =
-            filepath != null ? await getOriginalContent(filepath) : undefined
+          let originalContent: string | undefined
+          if (type === 'js' && result.map == null) {
+            const filepath = (
+              await server.moduleGraph.getModuleByUrl(url, false)
+            )?.file
+            originalContent =
+              filepath != null ? await getOriginalContent(filepath) : undefined
+          }
           return send(req, res, result.code, type, {
             etag: result.etag,
             // allow browser to cache npm deps!
diff --git a/packages/vite/src/node/server/send.ts b/packages/vite/src/node/server/send.ts
index c6de7452824665..414fa4fe998175 100644
--- a/packages/vite/src/node/server/send.ts
+++ b/packages/vite/src/node/server/send.ts
@@ -27,7 +27,7 @@ export interface SendOptions {
   cacheControl?: string
   headers?: OutgoingHttpHeaders
   map?: SourceMap | { mappings: '' } | null
-  /** only used when map == null (when the fallback sourcemap is used) */
+  /** only used when type === 'js' && map == null (when the fallback sourcemap is used) */
   originalContent?: string
 }