diff --git a/lib/readline.js b/lib/readline.js
index 12fb97e1cbf134..d81d62c9230c91 100644
--- a/lib/readline.js
+++ b/lib/readline.js
@@ -588,8 +588,8 @@ Interface.prototype._wordRight = function() {
 function charLengthLeft(str, i) {
   if (i <= 0)
     return 0;
-  if (i > 1 && str.codePointAt(i - 2) > 2 ** 16 ||
-      str.codePointAt(i - 1) > 2 ** 16) {
+  if (i > 1 && str.codePointAt(i - 2) >= 2 ** 16 ||
+      str.codePointAt(i - 1) >= 2 ** 16) {
     return 2;
   }
   return 1;
@@ -598,7 +598,7 @@ function charLengthLeft(str, i) {
 function charLengthAt(str, i) {
   if (str.length <= i)
     return 0;
-  return str.codePointAt(i) > 2 ** 16 ? 2 : 1;
+  return str.codePointAt(i) >= 2 ** 16 ? 2 : 1;
 }
 
 Interface.prototype._deleteLeft = function() {