gistfile1.diff

diff --git a/src/org/jruby/RubyDir.java b/src/org/jruby/RubyDir.java
index a8d9508..19d5089 100644
--- a/src/org/jruby/RubyDir.java
+++ b/src/org/jruby/RubyDir.java
@@ -392,11 +392,10 @@ public class RubyDir extends RubyObject {
     @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = CompatVersion.RUBY1_8)
     public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
         Ruby runtime = recv.getRuntime();
-        runtime.checkSafeString(args[0]);
+        RubyString stringArg = args[0].convertToString();
+        runtime.checkSafeString(stringArg);
 
-        String path = args[0].convertToString().getUnicodeValue();
-
-        return mkdirCommon(runtime, path, args);
+        return mkdirCommon(runtime, stringArg.getUnicodeValue(), args);
     }