diff --git a/lib/thor/shell/basic.rb b/lib/thor/shell/basic.rb
index 71ce4071..1cccca72 100644
--- a/lib/thor/shell/basic.rb
+++ b/lib/thor/shell/basic.rb
@@ -372,7 +372,7 @@ def merge(destination, content) #:nodoc:
         Tempfile.open([File.basename(destination), File.extname(destination)], File.dirname(destination)) do |temp|
           temp.write content
           temp.rewind
-          system %(#{merge_tool} "#{temp.path}" "#{destination}")
+          system(merge_tool, temp.path, destination)
         end
       end