diff --git a/core/src/main/java/hudson/FilePath.java b/core/src/main/java/hudson/FilePath.java
index f5e3f18ba7..4fbc624dde 100644
--- a/core/src/main/java/hudson/FilePath.java
+++ b/core/src/main/java/hudson/FilePath.java
@@ -27,6 +27,7 @@ package hudson;
 
 import hudson.Launcher.LocalLauncher;
 import hudson.Launcher.RemoteLauncher;
+import hudson.os.PosixAPI;
 import jenkins.model.Jenkins;
 import hudson.model.TaskListener;
 import hudson.model.AbstractProject;
@@ -1432,32 +1433,12 @@ public final class FilePath implements Serializable {
     }
 
     /**
-     * Run chmod via libc if we can, otherwise fall back to Ant.
+     * Run chmod via jnr-posix
      */
     private static void _chmod(File f, int mask) throws IOException {
         if (Functions.isWindows())  return; // noop
 
-        try {
-            if(LIBC.chmod(f.getAbsolutePath(),mask)!=0) {
-                throw new IOException("Failed to chmod "+f+" : "+LIBC.strerror(Native.getLastError()));
-            }
-        } catch(NoClassDefFoundError e) {  // cf. https://groups.google.com/group/hudson-dev/browse_thread/thread/6d16c3e8ea0dbc9?hl=fr
-            _chmodAnt(f, mask);
-        } catch(UnsatisfiedLinkError e2) { // HUDSON-8155: use Ant's chmod task on non-GNU C systems
-            _chmodAnt(f, mask);
-        }
-    }
-
-    private static void _chmodAnt(File f, int mask) {
-        if (!CHMOD_WARNED) { // only warn this once to avoid flooding the log
-            CHMOD_WARNED = true;
-            LOGGER.warning("GNU C Library not available: Using Ant's chmod task instead.");
-        }
-        Chmod chmodTask = new Chmod();
-        chmodTask.setProject(new Project());
-        chmodTask.setFile(f);
-        chmodTask.setPerm(Integer.toOctalString(mask));
-        chmodTask.execute();
+        PosixAPI.jnr().chmod(f.getAbsolutePath(),mask);
     }
 
     private static boolean CHMOD_WARNED = false;
diff --git a/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java b/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
index 86f6995a0b..0593557398 100644
--- a/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
+++ b/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
@@ -57,6 +57,7 @@ import hudson.model.*;
 import hudson.model.Executor;
 import hudson.model.Node.Mode;
 import hudson.model.Queue.Executable;
+import hudson.os.PosixAPI;
 import hudson.remoting.Which;
 import hudson.security.ACL;
 import hudson.security.AbstractPasswordBasedSecurityRealm;
@@ -82,7 +83,6 @@ import hudson.tools.ToolProperty;
 import hudson.util.PersistedList;
 import hudson.util.ReflectionUtils;
 import hudson.util.StreamTaskListener;
-import hudson.util.jna.GNUCLibrary;
 
 import java.beans.PropertyDescriptor;
 import java.io.BufferedReader;
@@ -587,8 +587,9 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
         mvn.copyFrom(HudsonTestCase.class.getClassLoader().getResource(mavenVersion + "-bin.zip"));
         mvn.unzip(new FilePath(buildDirectory));
         // TODO: switch to tar that preserves file permissions more easily
-        if(!Functions.isWindows())
-            GNUCLibrary.LIBC.chmod(new File(mvnHome, "bin/mvn").getPath(),0755);
+        if(!Functions.isWindows()) {
+            PosixAPI.jnr().chmod(new File(mvnHome, "bin/mvn").getPath(), 0755);
+        }
 
         MavenInstallation mavenInstallation = new MavenInstallation("default",
                 mvnHome.getAbsolutePath(), NO_PROPERTIES);
@@ -611,8 +612,9 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
             File antHome = createTmpDir();
             ant.unzip(new FilePath(antHome));
             // TODO: switch to tar that preserves file permissions more easily
-            if(!Functions.isWindows())
-                GNUCLibrary.LIBC.chmod(new File(antHome,"apache-ant-1.8.1/bin/ant").getPath(),0755);
+            if(!Functions.isWindows()) {
+                PosixAPI.jnr().chmod(new File(antHome,"apache-ant-1.8.1/bin/ant").getPath(),0755);
+            }
 
             antInstallation = new AntInstallation("default", new File(antHome,"apache-ant-1.8.1").getAbsolutePath(),NO_PROPERTIES);
         }
@@ -1976,8 +1978,8 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
 
         if (!Functions.isWindows()) {
             try {
-                GNUCLibrary.LIBC.unsetenv("MAVEN_OPTS");
-                GNUCLibrary.LIBC.unsetenv("MAVEN_DEBUG_OPTS");
+                PosixAPI.jnr().unsetenv("MAVEN_OPTS");
+                PosixAPI.jnr().unsetenv("MAVEN_DEBUG_OPTS");
             } catch (Exception e) {
                 LOGGER.log(Level.WARNING,"Failed to cancel out MAVEN_OPTS",e);
             }