diff --git a/.changeset/seven-rice-exercise.md b/.changeset/seven-rice-exercise.md
new file mode 100644
index 0000000000..2e2d62b596
--- /dev/null
+++ b/.changeset/seven-rice-exercise.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes the user-facing type of the new `i18n.routing.fallbackType` option to be optional
diff --git a/packages/astro/src/@types/astro.ts b/packages/astro/src/@types/astro.ts
index 0b4f7c0ef3..9087858f11 100644
--- a/packages/astro/src/@types/astro.ts
+++ b/packages/astro/src/@types/astro.ts
@@ -1703,7 +1703,7 @@ export interface AstroUserConfig {
 					 * })
 					 * ```
 					 */
-					fallbackType: 'redirect' | 'rewrite';
+					fallbackType?: 'redirect' | 'rewrite';
 
 					/**
 					 * @name i18n.routing.strategy