diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go
index 45ccc806bdf..cb73caf3bb7 100644
--- a/src/runtime/mgcmark.go
+++ b/src/runtime/mgcmark.go
@@ -1257,12 +1257,7 @@ func scanobject(b uintptr, gcw *gcWork) {
 	}
 
 	var i uintptr
-	for i = 0; i < n; i += sys.PtrSize {
-		// Find bits for this word.
-		if i != 0 {
-			// Avoid needless hbits.next() on last iteration.
-			hbits = hbits.next()
-		}
+	for i = 0; i < n; i, hbits = i+sys.PtrSize, hbits.next() {
 		// Load bits once. See CL 22712 and issue 16973 for discussion.
 		bits := hbits.bits()
 		if bits&bitScan == 0 {