diff --git a/lib/cocaine/command_line.rb b/lib/cocaine/command_line.rb
index 7bb70d6..0b2ae0b 100644
--- a/lib/cocaine/command_line.rb
+++ b/lib/cocaine/command_line.rb
@@ -166,9 +166,8 @@ def shell_quote_all_values(values)
 
     def shell_quote(string)
       return "" if string.nil?
-      if string.respond_to? :to_s
-        string = string.to_s
-      end
+      string = string.to_s if string.respond_to? :to_s
+
       if OS.unix?
         if string.empty?
           "''"