diff --git a/kernel/src/device/random.rs b/kernel/src/device/random.rs
index f614c9f4c..2f04c1df9 100644
--- a/kernel/src/device/random.rs
+++ b/kernel/src/device/random.rs
@@ -47,7 +47,9 @@ impl Pollable for Random {
 impl FileIo for Random {
     fn read(&self, writer: &mut VmWriter) -> Result<usize> {
         let mut buf = vec![0; writer.avail()];
-        Self::getrandom(buf.as_mut_slice())
+        let size = Self::getrandom(buf.as_mut_slice());
+        writer.write_fallible(&mut buf.as_slice().into())?;
+        size
     }
 
     fn write(&self, reader: &mut VmReader) -> Result<usize> {
diff --git a/kernel/src/device/urandom.rs b/kernel/src/device/urandom.rs
index 04e5d8121..faace7a71 100644
--- a/kernel/src/device/urandom.rs
+++ b/kernel/src/device/urandom.rs
@@ -47,7 +47,9 @@ impl Pollable for Urandom {
 impl FileIo for Urandom {
     fn read(&self, writer: &mut VmWriter) -> Result<usize> {
         let mut buf = vec![0; writer.avail()];
-        Self::getrandom(buf.as_mut_slice())
+        let size = Self::getrandom(buf.as_mut_slice());
+        writer.write_fallible(&mut buf.as_slice().into())?;
+        size
     }
 
     fn write(&self, reader: &mut VmReader) -> Result<usize> {