diff --git a/core/src/main/java/org/jruby/util/IOOutputStream.java b/core/src/main/java/org/jruby/util/IOOutputStream.java
index b9805280c6f..dd1507eb4a9 100644
--- a/core/src/main/java/org/jruby/util/IOOutputStream.java
+++ b/core/src/main/java/org/jruby/util/IOOutputStream.java
@@ -36,6 +36,7 @@
 import org.jruby.RubyIO;
 import org.jruby.RubyString;
 import org.jruby.runtime.CallSite;
+import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
 import org.jruby.runtime.MethodIndex;
 
@@ -52,7 +53,8 @@
  */
 public class IOOutputStream extends OutputStream {
     private final IRubyObject io;
-    private final OutputStream out;
+    private final RubyIO realIO;
+    private final Ruby runtime;
     private final CallSite writeAdapter;
     private final CallSite closeAdapter = MethodIndex.getFunctionalCallSite("close");
     private final Encoding encoding;
@@ -64,10 +66,11 @@ public class IOOutputStream extends OutputStream {
      */
     public IOOutputStream(final IRubyObject io, Encoding encoding, boolean checkAppend, boolean verifyCanWrite) {
         this.io = io;
-        this.out = ( io instanceof RubyIO && !((RubyIO) io).isClosed() &&
+        this.runtime = io.getRuntime();
+        this.realIO = ( io instanceof RubyIO && !((RubyIO) io).isClosed() &&
                 ((RubyIO) io).isBuiltin("write") ) ?
-                    ((RubyIO) io).getOutStream() : null;
-        if (out == null || verifyCanWrite) {
+                    ((RubyIO) io) : null;
+        if (realIO == null || verifyCanWrite) {
             final String site;
             if (io.respondsTo("write")) {
                 site = "write";
@@ -106,12 +109,16 @@ public IOOutputStream(final IRubyObject io, Encoding encoding) {
 
     @Override
     public void write(final int bite) throws IOException {
-        if (out != null) {
-            out.write(bite);
+        ThreadContext context = runtime.getCurrentContext();
+
+        RubyString str = RubyString.newStringLight(runtime, new ByteList(new byte[]{(byte) bite}, encoding, false));
+
+        RubyIO realIO = this.realIO;
+        if (realIO != null) {
+            realIO.write(context, str);
         } else {
-            final Ruby runtime = io.getRuntime();
-            writeAdapter.call(runtime.getCurrentContext(), io, io,
-                    RubyString.newStringLight(runtime, new ByteList(new byte[] { (byte) bite }, encoding, false)));
+            IRubyObject io = this.io;
+            writeAdapter.call(context, io, io, str);
         }
     }
 
@@ -122,21 +129,31 @@ public void write(final byte[] b) throws IOException {
 
     @Override
     public void write(final byte[] b,final int off, final int len) throws IOException {
-        if (out != null) {
-            out.write(b, off, len);
+        ThreadContext context = runtime.getCurrentContext();
+
+        RubyString str = RubyString.newStringLight(runtime, new ByteList(b, off, len, encoding, false));
+
+        RubyIO realIO = this.realIO;
+        if (realIO != null) {
+            realIO.write(context, str);
         } else {
-            final Ruby runtime = io.getRuntime();
-            writeAdapter.call(runtime.getCurrentContext(), io, io,
-                    RubyString.newStringLight(runtime, new ByteList(b, off, len, encoding, false)));
+            IRubyObject io = this.io;
+            writeAdapter.call(context, io, io, str);
         }
     }
     
     @Override
     public void close() throws IOException {
-        if (out != null) {
-            out.close();
-        } else if (io.respondsTo("close")) {
-            closeAdapter.call(io.getRuntime().getCurrentContext(), io, io);
+        ThreadContext context = runtime.getCurrentContext();
+
+        RubyIO realIO = this.realIO;
+        if (realIO != null) {
+            realIO.close(context);
+        } else {
+            IRubyObject io = this.io;
+            if (io.respondsTo("close")) {
+                closeAdapter.call(context, io, io);
+            }
         }
     }
 }