RUBYOPT is not recognized as a command about syntastic HOT 4 CLOSED

diff --git a/syntax_checkers/ruby.vim b/syntax_checkers/ruby.vim
index b15deca..a0e5211 100644
--- a/syntax_checkers/ruby.vim
+++ b/syntax_checkers/ruby.vim
@@ -20,7 +20,7 @@ if !executable("ruby")
 endif

 function! SyntaxCheckers_ruby_GetLocList()
-    let makeprg = 'RUBYOPT= ruby -W1 -c '.shellescape(expand('%'))
+    let makeprg = 'ruby -W1 -c '.shellescape(expand('%'))
     let errorformat =  '%-GSyntax OK,%E%f:%l: syntax error\, %m,%Z%p^,%W%f:%l: warning: %m,%Z%p^,%-C%.%#'

     return SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })