diff --git a/.changeset/afraid-rivers-begin.md b/.changeset/afraid-rivers-begin.md
new file mode 100644
index 0000000000..39341ff52e
--- /dev/null
+++ b/.changeset/afraid-rivers-begin.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Reverts [#11292](https://github.com/withastro/astro/pull/11292), which caused a regression to the input type
diff --git a/packages/astro/src/actions/runtime/virtual/server.ts b/packages/astro/src/actions/runtime/virtual/server.ts
index d52a284ce3..ce4d5f6966 100644
--- a/packages/astro/src/actions/runtime/virtual/server.ts
+++ b/packages/astro/src/actions/runtime/virtual/server.ts
@@ -50,7 +50,7 @@ export type ActionClient<
 
 export function defineAction<
 	TOutput,
-	TAccept extends Accept,
+	TAccept extends Accept = 'json',
 	TInputSchema extends InputSchema<Accept> | undefined = TAccept extends 'form'
 		? // If `input` is omitted, default to `FormData` for forms and `any` for JSON.
 			z.ZodType<FormData>