diff --git a/src/scheme/debug.rs b/src/scheme/debug.rs
index 23eb049..f97452b 100644
--- a/src/scheme/debug.rs
+++ b/src/scheme/debug.rs
@@ -47,7 +47,11 @@ impl Scheme for DebugScheme {
         Ok(id)
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let flags = {
             let handles = self.handles.read();
             *handles.get(&id).ok_or(Error::new(EBADF))?
diff --git a/src/scheme/env.rs b/src/scheme/env.rs
index 112d896..cbe5b7e 100644
--- a/src/scheme/env.rs
+++ b/src/scheme/env.rs
@@ -90,7 +90,11 @@ impl Scheme for EnvScheme {
         }
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let new_handle = {
             let handles = self.handles.read();
             let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/event.rs b/src/scheme/event.rs
index f68c2a3..24afc1e 100644
--- a/src/scheme/event.rs
+++ b/src/scheme/event.rs
@@ -39,7 +39,11 @@ impl Scheme for EventScheme {
         Ok(id)
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let handle = {
             let handles = self.handles.read();
             let handle_weak = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/initfs.rs b/src/scheme/initfs.rs
index 7c099aa..7f9b7dd 100644
--- a/src/scheme/initfs.rs
+++ b/src/scheme/initfs.rs
@@ -65,7 +65,11 @@ impl Scheme for InitFsScheme {
         Err(Error::new(ENOENT))
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let (path, flags, data, mode, seek) = {
             let handles = self.handles.read();
             let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/irq.rs b/src/scheme/irq.rs
index a5c0333..854cc99 100644
--- a/src/scheme/irq.rs
+++ b/src/scheme/irq.rs
@@ -48,7 +48,11 @@ impl Scheme for IrqScheme {
         }
     }
 
-    fn dup(&self, file: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, file: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         Ok(file)
     }
 
diff --git a/src/scheme/live.rs b/src/scheme/live.rs
index e434f8e..bc6b845 100644
--- a/src/scheme/live.rs
+++ b/src/scheme/live.rs
@@ -49,7 +49,11 @@ impl Scheme for DiskScheme {
         Ok(id)
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let (path, data, mode, seek) = {
             let handles = self.handles.read();
             let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/null.rs b/src/scheme/null.rs
index 81b6454..c8df593 100644
--- a/src/scheme/null.rs
+++ b/src/scheme/null.rs
@@ -8,7 +8,11 @@ impl Scheme for NullScheme {
         Ok(0)
     }
 
-    fn dup(&self, _file: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, _file: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         Ok(0)
     }
 
diff --git a/src/scheme/pipe.rs b/src/scheme/pipe.rs
index 342fb1f..0989e84 100644
--- a/src/scheme/pipe.rs
+++ b/src/scheme/pipe.rs
@@ -51,7 +51,11 @@ impl PipeScheme {
 }
 
 impl Scheme for PipeScheme {
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let mut pipes = pipes_mut();
 
         let read_option = if let Some(pipe) = pipes.0.get(&id) {
diff --git a/src/scheme/root.rs b/src/scheme/root.rs
index 42bcaad..6261ff7 100644
--- a/src/scheme/root.rs
+++ b/src/scheme/root.rs
@@ -71,7 +71,11 @@ impl Scheme for RootScheme {
         }
     }
 
-    fn dup(&self, file: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, file: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let mut handles = self.handles.write();
         let inner = {
             let inner = handles.get(&file).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/sys/mod.rs b/src/scheme/sys/mod.rs
index a058dbf..63ddfd2 100644
--- a/src/scheme/sys/mod.rs
+++ b/src/scheme/sys/mod.rs
@@ -100,7 +100,11 @@ impl Scheme for SysScheme {
         Err(Error::new(ENOENT))
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let (path, data, mode, seek) = {
             let handles = self.handles.read();
             let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
diff --git a/src/scheme/time.rs b/src/scheme/time.rs
index faef360..b41bad6 100644
--- a/src/scheme/time.rs
+++ b/src/scheme/time.rs
@@ -45,7 +45,11 @@ impl Scheme for TimeScheme {
         Ok(id)
     }
 
-    fn dup(&self, id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, id: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let clock = {
             let handles = self.handles.read();
             *handles.get(&id).ok_or(Error::new(EBADF))?
diff --git a/src/scheme/zero.rs b/src/scheme/zero.rs
index 194f2ec..e2a202b 100644
--- a/src/scheme/zero.rs
+++ b/src/scheme/zero.rs
@@ -8,7 +8,11 @@ impl Scheme for ZeroScheme {
         Ok(0)
     }
 
-    fn dup(&self, _file: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, _file: usize, buf: &[u8]) -> Result<usize> {
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         Ok(0)
     }