diff --git a/packages/vite/src/node/plugins/css.ts b/packages/vite/src/node/plugins/css.ts
index 4956a90ca5fff9..ced7ddb77117f4 100644
--- a/packages/vite/src/node/plugins/css.ts
+++ b/packages/vite/src/node/plugins/css.ts
@@ -377,7 +377,9 @@ export function cssPostPlugin(config: ResolvedConfig): Plugin {
         const getContentWithSourcemap = async (content: string) => {
           if (config.css?.devSourcemap) {
             const sourcemap = this.getCombinedSourcemap()
-            await injectSourcesContent(sourcemap, cleanUrl(id), config.logger)
+            if (sourcemap.mappings && !sourcemap.sourcesContent) {
+              await injectSourcesContent(sourcemap, cleanUrl(id), config.logger)
+            }
             return getCodeWithSourcemap('css', content, sourcemap)
           }
           return content