diff --git a/src/strings/replace.go b/src/strings/replace.go
index ccab1fb861d..e28d4288793 100644
--- a/src/strings/replace.go
+++ b/src/strings/replace.go
@@ -25,7 +25,8 @@ type replacer interface {
 
 // NewReplacer returns a new Replacer from a list of old, new string
 // pairs. Replacements are performed in the order they appear in the
-// target string, without overlapping matches.
+// target string, without overlapping matches. The old string
+// comparisons are done in argument order.
 //
 // NewReplacer panics if given an odd number of arguments.
 func NewReplacer(oldnew ...string) *Replacer {