diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 00000000..757fd64c
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,3 @@
+{
+  "trailingComma": "es5"
+}
diff --git a/src/utils.ts b/src/utils.ts
index 15bc2a04..ac8db879 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -46,7 +46,7 @@ export interface ResponseMap {
 export type ResponseType = keyof ResponseMap | "json";
 export type MappedType<
   R extends ResponseType,
-  JsonType = any
+  JsonType = any,
 > = R extends keyof ResponseMap ? ResponseMap[R] : JsonType;
 
 // This provides reasonable defaults for the correct parser based on Content-Type header.