diff --git a/.changeset/rotten-cups-happen.md b/.changeset/rotten-cups-happen.md
new file mode 100644
index 000000000000..e484c098f790
--- /dev/null
+++ b/.changeset/rotten-cups-happen.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix duplicate CSS in dev mode when `vite.css.devSourcemap` is provided