diff --git a/lib/webrick/server.rb b/lib/webrick/server.rb
index ca5e435..a774fe6 100644
--- a/lib/webrick/server.rb
+++ b/lib/webrick/server.rb
@@ -103,7 +103,11 @@ module WEBrick
       @shutdown_pipe = nil
       unless @config[:DoNotListen]
         if @config[:Listen]
-          warn(":Listen option is deprecated; use GenericServer#listen")
+          if RUBY_VERSION < "2.5"
+            warn(":Listen option is deprecated; use GenericServer#listen")
+          else
+            warn(":Listen option is deprecated; use GenericServer#listen", uplevel: 1)
+          end
         end
         listen(@config[:BindAddress], @config[:Port])
         if @config[:Port] == 0
diff --git a/lib/webrick/utils.rb b/lib/webrick/utils.rb
index 68833af..9b28db1 100644
--- a/lib/webrick/utils.rb
+++ b/lib/webrick/utils.rb
@@ -37,7 +37,11 @@ module WEBrick
         Process::Sys::setgid(pw.gid)
         Process::Sys::setuid(pw.uid)
       else
-        warn("WEBrick::Utils::su doesn't work on this platform")
+        if RUBY_VERSION < "2.5"
+          warn("WEBrick::Utils::su doesn't work on this platform")
+        else
+          warn("WEBrick::Utils::su doesn't work on this platform", uplevel: 1)
+        end
       end
     end
     module_function :su