diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index a024dd167..f508f6e58 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -1878,10 +1878,6 @@ class TestInvalidFD(unittest.TestCase):
             if  hasattr(os, f):
                 self.check(getattr(os, f))
 
-        # TODO: RUSTPYTHON; io.FileIO(fd) should check if the fd passed is valid
-        if f == "fdopen":
-            # this is test_fdopen
-            helper = unittest.expectedFailure(helper)
 
         return helper
     for f in singles:
diff --git a/vm/src/stdlib/io.rs b/vm/src/stdlib/io.rs
index a1b86fd5d..d18d8be30 100644
--- a/vm/src/stdlib/io.rs
+++ b/vm/src/stdlib/io.rs
@@ -8,6 +8,9 @@ cfg_if::cfg_if! {
         type Offset = i64;
     }
 }
+
+#[cfg(unix)]
+use crate::stdlib::os::{errno_err, PathOrFd};
 use crate::VirtualMachine;
 use crate::{PyObjectRef, PyResult, TryFromObject};
 pub(crate) use _io::io_open as open;
@@ -3571,6 +3574,12 @@ mod _io {
             }
         }
 
+        // check file descriptor validity
+        #[cfg(unix)]
+        if let Ok(PathOrFd::Fd(fd)) = PathOrFd::try_from_object(vm, file.clone()) {
+            nix::fcntl::fcntl(fd, nix::fcntl::F_GETFD).map_err(|_| errno_err(vm))?;
+        }
+
         // Construct a FileIO (subclass of RawIOBase)
         // This is subsequently consumed by a Buffered Class.
         let file_io_class = {
diff --git a/vm/src/stdlib/os.rs b/vm/src/stdlib/os.rs
index e3b853710..24a883cf1 100644
--- a/vm/src/stdlib/os.rs
+++ b/vm/src/stdlib/os.rs
@@ -217,7 +217,7 @@ impl TryFromObject for PyPathLike {
     }
 }
 
-enum PathOrFd {
+pub(crate) enum PathOrFd {
     Path(PyPathLike),
     Fd(i32),
 }