diff --git a/src/helpers.ts b/src/helpers.ts
index af652cf..0656419 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -10,7 +10,7 @@ export async function map_concurrent<In, Out>(
   map_fn: (input: In) => Promise<Out | null>,
 ): Promise<Map<In, Out | null>> {
   // apply map_fn to inputs
-  const outputs = await Promise.all([...inputs].map((input) => map_fn(input)));
+  const outputs = await Promise.all([...inputs].map(map_fn));
 
   // create map object
   return new Map<In, Out | null>(