diff --git a/packages/custom-client/src/core/bodySerializer.ts b/packages/custom-client/src/core/bodySerializer.ts
index 9077af6505..5c23e0fc47 100644
--- a/packages/custom-client/src/core/bodySerializer.ts
+++ b/packages/custom-client/src/core/bodySerializer.ts
@@ -50,6 +50,10 @@ export const formDataBodySerializer = {
   bodySerializer: <T extends Record<string, any> | Array<Record<string, any>>>(
     body: T,
   ): FormData => {
+    if (body instanceof FormData) {
+      return body;
+    }
+    
     const data = new FormData();
 
     Object.entries(body).forEach(([key, value]) => {