diff --git a/lib/reline/line_editor.rb b/lib/reline/line_editor.rb
index b095c70de9..cba90fde05 100644
--- a/lib/reline/line_editor.rb
+++ b/lib/reline/line_editor.rb
@@ -82,9 +82,7 @@ class Reline::LineEditor
   MenuInfo = Struct.new('MenuInfo', :target, :list)
 
   CSI_REGEXP = /\e\[[\d;]*[ABCDEFGHJKSTfminsuhl]/
-  OSC_REGEXP = /\e\]\d+(?:;[^;]+)*\a/
-  NON_PRINTING_START = "\1"
-  NON_PRINTING_END = "\2"
+  NON_PRINTING_ESCAPES = "\1\2"
 
   def initialize(config)
     @config = config
@@ -182,31 +180,19 @@ class Reline::LineEditor
     lines = [String.new(encoding: @encoding)]
     height = 1
     width = 0
+    prompt = prompt.tr(NON_PRINTING_ESCAPES, '')
+    str = str.tr(NON_PRINTING_ESCAPES, '')
     rest = "#{prompt}#{str}".encode(Encoding::UTF_8)
-    in_zero_width = false
     loop do
       break if rest.empty?
-      if rest.start_with?(NON_PRINTING_START)
-        rest.delete_prefix!(NON_PRINTING_START)
-        in_zero_width = true
-      elsif rest.start_with?(NON_PRINTING_END)
-        rest.delete_prefix!(NON_PRINTING_END)
-        in_zero_width = false
-      elsif rest.start_with?(CSI_REGEXP)
-        lines.last << $&
-        rest = $'
-      elsif rest.start_with?(OSC_REGEXP)
+      if rest =~ /\A#{CSI_REGEXP}/
         lines.last << $&
         rest = $'
       else
         gcs = rest.grapheme_clusters
         gc = gcs.first
         rest = gcs[1..-1].join
-        if in_zero_width
-          mbchar_width = 0
-        else
-          mbchar_width = Reline::Unicode.get_mbchar_width(gc)
-        end
+        mbchar_width = Reline::Unicode.get_mbchar_width(gc)
         width += mbchar_width
         if width > max_width
           width = mbchar_width
@@ -839,41 +825,14 @@ class Reline::LineEditor
     new_str
   end
 
-  private def calculate_width(str, allow_escape_code = false)
-    width = 0
-    rest = str.encode(Encoding::UTF_8)
-    in_zero_width = false
-    if allow_escape_code
-      loop do
-        break if rest.empty?
-        if rest.start_with?(NON_PRINTING_START)
-          rest.delete_prefix!(NON_PRINTING_START)
-          in_zero_width = true
-        elsif rest.start_with?(NON_PRINTING_END)
-          rest.delete_prefix!(NON_PRINTING_END)
-          in_zero_width = false
-        elsif rest.start_with?(CSI_REGEXP)
-          rest = $'
-        elsif rest.start_with?(OSC_REGEXP)
-          rest = $'
-        else
-          gcs = rest.grapheme_clusters
-          gc = gcs.first
-          rest = gcs[1..-1].join
-          if in_zero_width
-            mbchar_width = 0
-          else
-            mbchar_width = Reline::Unicode.get_mbchar_width(gc)
-          end
-          width += mbchar_width
-        end
-      end
-    else
-      str.encode(Encoding::UTF_8).grapheme_clusters.inject(0) { |width, gc|
-        width + Reline::Unicode.get_mbchar_width(gc)
-      }
+  private def calculate_width(str, allow_csi = false)
+    if allow_csi
+      str = str.gsub(CSI_REGEXP, '')
+      str = str.tr(NON_PRINTING_ESCAPES, '')
     end
-    width
+    str.encode(Encoding::UTF_8).grapheme_clusters.inject(0) { |width, gc|
+      width + Reline::Unicode.get_mbchar_width(gc)
+    }
   end
 
   private def key_delete(key)