diff --git a/src/runtime/mkduff.go b/src/runtime/mkduff.go
index 6c7a4cf8dc7..8859ed68ccb 100644
--- a/src/runtime/mkduff.go
+++ b/src/runtime/mkduff.go
@@ -83,7 +83,6 @@ func copyAMD64(w io.Writer) {
 	//
 	// This is equivalent to a sequence of MOVSQ but
 	// for some reason that is 3.5x slower than this code.
-	// The STOSQ in duffzero seem fine, though.
 	fmt.Fprintln(w, "TEXT runtime·duffcopy(SB), NOSPLIT, $0-0")
 	for i := 0; i < 64; i++ {
 		fmt.Fprintln(w, "\tMOVUPS\t(SI), X0")