--- .classpath
+++ .classpath
@@ -35,8 +35,11 @@
 	<classpathentry kind="lib" path="extlibs/jffi-x86_64-Linux.jar"/>
 	<classpathentry kind="lib" path="extlibs/jffi-x86_64-OpenBSD.jar"/>
 	<classpathentry kind="lib" path="extlibs/jffi-x86_64-SunOS.jar"/>
-	<classpathentry kind="lib" path="extlibs/jffi.jar"/>
-	<classpathentry kind="lib" path="extlibs/jnr-posix.jar"/>
+	<classpathentry kind="lib" path="extlibs/jffi-1.2.2-SNAPSHOT.jar"/>
+	<classpathentry kind="lib" path="extlibs/jnr-constants-0.8.3-SNAPSHOT.jar"/>
+	<classpathentry kind="lib" path="extlibs/jnr-ffi-0.7.4-SNAPSHOT.jar"/>
+	<classpathentry kind="lib" path="extlibs/jnr-netdb-1.0.6-SNAPSHOT.jar"/>
+	<classpathentry kind="lib" path="extlibs/jnr-posix-2.1-SNAPSHOT.jar"/>
 	<classpathentry kind="lib" path="extlibs/guava-r07.jar"/>
 	<classpathentry kind="output" path="build/classes"/>
 </classpath>
--- build.xml
+++ build.xml
@@ -208,9 +208,11 @@
             <pathelement path="${extlibs.dir}/jffi-x86_64-OpenBSD.jar"/>
             <pathelement path="${extlibs.dir}/jffi-x86_64-SunOS.jar"/>
             <pathelement path="${extlibs.dir}/jffi-x86_64-Windows.jar"/>
-            <pathelement path="${extlibs.dir}/jffi.jar"/>
-            <pathelement path="${extlibs.dir}/jnr-posix.jar"/>
-            <pathelement path="${extlibs.dir}/jnr-netdb-0.4.jar"/>
+            <pathelement path="${extlibs.dir}/jffi-1.2.2-SNAPSHOT.jar"/>
+            <pathelement path="${extlibs.dir}/jnr-constants-0.8.3-SNAPSHOT.jar"/>
+            <pathelement path="${extlibs.dir}/jnr-ffi-0.7.4-SNAPSHOT.jar"/>
+            <pathelement path="${extlibs.dir}/jnr-netdb-1.0.6-SNAPSHOT.jar"/>
+            <pathelement path="${extlibs.dir}/jnr-posix-2.1-SNAPSHOT.jar"/>
         </path>
 
         <available property="informix.present" classname="com.informix.jdbc.IfxDriver" classpath="${informix.jar}" />
--- src/org/python/core/Py.java
+++ src/org/python/core/Py.java
@@ -130,6 +130,14 @@
         return OSError(errno, Py.newString(filename));
     }
 
+    public static PyException OSError(jnr.constants.Constant errno, PyObject filename) {
+        int value = errno.intValue();
+        // Pass to strerror because constantine currently lacks Errno descriptions on
+        // Windows, and strerror falls back to Linux's
+        PyObject args = new PyTuple(Py.newInteger(value), PosixModule.strerror(value), filename);
+        return new PyException(Py.OSError, args);
+    }
+
     public static PyObject NotImplementedError;
     public static PyException NotImplementedError(String message) {
         return new PyException(Py.NotImplementedError, message);
--- src/org/python/core/PySystemState.java
+++ src/org/python/core/PySystemState.java
@@ -27,7 +27,7 @@
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.util.Platform;
 import org.python.Version;
 import org.python.core.adapter.ClassicPyObjectAdapter;
 import org.python.core.adapter.ExtensiblePyObjectAdapter;
--- src/org/python/core/io/FileIO.java
+++ src/org/python/core/io/FileIO.java
@@ -13,7 +13,7 @@
 import java.nio.channels.FileChannel;
 
 import com.kenai.constantine.platform.Errno;
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.util.Platform;
 import org.python.core.Py;
 import org.python.core.PyString;
 import org.python.core.util.RelativeFile;
--- src/org/python/core/util/PlatformUtil.java
+++ src/org/python/core/util/PlatformUtil.java
@@ -1,7 +1,7 @@
 /* Copyright (c) 2009 Jython project */
 package org.python.core.util;
 
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.util.Platform;
 
 /**
  * Methods for testing the platform/operating system that we are on.
--- src/org/python/modules/errno.java
+++ src/org/python/modules/errno.java
@@ -4,7 +4,7 @@
 import com.kenai.constantine.Constant;
 import com.kenai.constantine.ConstantSet;
 import com.kenai.constantine.platform.Errno;
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.util.Platform;
 import org.python.core.ClassDictInit;
 import org.python.core.Py;
 import org.python.core.PyDictionary;
--- src/org/python/modules/posix/PosixModule.java
+++ src/org/python/modules/posix/PosixModule.java
@@ -17,10 +17,10 @@
 import java.util.Iterator;
 import java.util.Map;
 
-import org.jruby.ext.posix.FileStat;
-import org.jruby.ext.posix.POSIX;
-import org.jruby.ext.posix.POSIXFactory;
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.FileStat;
+import jnr.posix.POSIX;
+import jnr.posix.POSIXFactory;
+import jnr.posix.util.Platform;
 
 import org.python.core.ClassDictInit;
 import org.python.core.Py;
--- src/org/python/modules/posix/PyStatResult.java
+++ src/org/python/modules/posix/PyStatResult.java
@@ -1,7 +1,7 @@
 /* Copyright (c) Jython Developers */
 package org.python.modules.posix;
 
-import org.jruby.ext.posix.FileStat;
+import jnr.posix.FileStat;
 
 import org.python.core.ArgParser;
 import org.python.core.Py;
--- src/org/python/modules/posix/PythonPOSIXHandler.java
+++ src/org/python/modules/posix/PythonPOSIXHandler.java
@@ -1,26 +1,26 @@
 /* Copyright (c) Jython Developers */
 package org.python.modules.posix;
 
-import com.kenai.constantine.platform.Errno;
-
 import java.io.File;
 import java.io.InputStream;
 import java.io.PrintStream;
 
-import org.jruby.ext.posix.POSIX;
-import org.jruby.ext.posix.POSIXHandler;
+import jnr.constants.platform.Errno;
+import jnr.posix.POSIX;
+import jnr.posix.POSIXHandler;
 
 import org.python.core.imp;
 import org.python.core.Options;
 import org.python.core.Py;
 import org.python.core.PyObject;
 
+
 /**
  * Jython specific hooks for our underlying POSIX library.
  */
 public class PythonPOSIXHandler implements POSIXHandler {
 
-    public void error(Errno error, String extraData) {
+	public void error(Errno error, String extraData) {
         // XXX: extraData (filename) could have been unicode!
         // http://bugs.jython.org/issue1825
         throw Py.OSError(error, Py.newString(extraData));
--- tests/java/org/python/core/PySystemStateTest.java
+++ tests/java/org/python/core/PySystemStateTest.java
@@ -7,7 +7,7 @@
 
 import junit.framework.TestCase;
 
-import org.jruby.ext.posix.util.Platform;
+import jnr.posix.util.Platform;
 
 public class PySystemStateTest extends TestCase {