diff --git a/src/main.d.mts b/src/main.d.mts
index 927e6ef..1887bb8 100644
--- a/src/main.d.mts
+++ b/src/main.d.mts
@@ -67,6 +67,7 @@ interface k_options {
 
 // ---
 export function bench(fn: () => any): B;
+export function bench(fn: B): B;
 export function do_not_optimize(v: any): void;
 export function bench(name: string, fn: () => any): B;
 export function bench(gen: (state: k_state) => Gen): B;
@@ -149,4 +150,4 @@ export class B {
   name(name: string, highlight?: Color): this;
   range(name: string, s: number, e: number, multiplier?: number): this;
   dense_range(name: string, s: number, e: number, accumulator?: number): this;
-}
\ No newline at end of file
+}
diff --git a/src/main.mjs b/src/main.mjs
index d0b58fa..3eb42ff 100644
--- a/src/main.mjs
+++ b/src/main.mjs
@@ -202,10 +202,17 @@ export function lineplot(f) { return _c(f, 'l'); }
 export function group(name, f) { if (typeof name === 'function') (f = name, name = null); return _c(f, 'g', name); }
 
 export function bench(n, fn) {
-  if (typeof n === 'function') (fn = n, n = fn.name || 'anonymous');
+  let b;
+  if(n instanceof B) {
+    b = n
+  }else {
+    if (typeof n === 'function') (fn = n, n = fn.name || 'anonymous');
+    b = new B(n, fn);
+  }
 
   const collection = COLLECTIONS[COLLECTIONS.length - 1];
-  const b = new B(n, fn); b._group = collection.id; return (collection.trials.push(b), b);
+  b._group = collection.id;
+  return (collection.trials.push(b), b);
 }
 
 export function compact(f) {
@@ -1592,4 +1599,4 @@ export const $ = {
       canvas[canvas.length - 1] += !colors ? rmax : ($.magenta + rmax + $.reset); return canvas;
     },
   },
-};
\ No newline at end of file
+};