diff --git a/lib/pry/terminal.rb b/lib/pry/terminal.rb
index d88716b0..67f2979f 100644
--- a/lib/pry/terminal.rb
+++ b/lib/pry/terminal.rb
@@ -54,7 +54,7 @@ class Pry::Terminal
     end
 
     def screen_size_according_to_readline
-      if Readline.respond_to?(:get_screen_size)
+      if defined?(Readline) && Readline.respond_to?(:get_screen_size)
         size = Readline.get_screen_size
         size if nonzero_column?(size)
       end