diff --git a/otp/userdb.rb b/otp/userdb.rb
index d0b9aaa..78e2935 100644
--- a/otp/userdb.rb
+++ b/otp/userdb.rb
@@ -38,6 +38,7 @@
     rcpt = rcpt.join(" ") if rcpt.is_a?(Array)
     sj = NKF.nkf('-jM', subj)
     body = NKF.nkf('-j', body)
+    ENV["PATH"] = "/bin:/usr/bin:/usr/sbin:/usr/local/bin "
     open("| sendmail -f #{@from} #{rcpt}", "w") do |m|
       m.puts(<<~EOF)
         Subject: #{sj}