diff --git a/lib/reline/ansi.rb b/lib/reline/ansi.rb
index 36ac7257e8..10f112964c 100644
--- a/lib/reline/ansi.rb
+++ b/lib/reline/ansi.rb
@@ -112,10 +112,11 @@ def self.cursor_pos
       @@input.raw do |stdin|
         @@output << "\e[6n"
         @@output.flush
-        while (c = stdin.getc) != 'R'
-          res << c if c
+        while (c = stdin.getc)
+          res << c
+          m = res.match(/\e\[(?<row>\d+);(?<column>\d+)R/)
+          break if m
         end
-        m = res.match(/\e\[(?<row>\d+);(?<column>\d+)/)
         (m.pre_match + m.post_match).chars.reverse_each do |ch|
           stdin.ungetc ch
         end