diff --git a/vm/src/exceptions.rs b/vm/src/exceptions.rs
index 9e4b87a8f..e9622f78e 100644
--- a/vm/src/exceptions.rs
+++ b/vm/src/exceptions.rs
@@ -672,6 +672,14 @@ impl ExceptionZoo {
             "__str__" => ctx.new_method("__str__", key_error_str),
         });
 
+        extend_class!(ctx, &excs.os_error, {
+            "errno" => ctx.new_readonly_getset("errno", |exc: PyBaseExceptionRef| {
+                let args = exc.args();
+                let args = args.borrow_value();
+                args.get(0).filter(|_| args.len() > 1).cloned()
+            }),
+        });
+
         extend_class!(ctx, &excs.unicode_decode_error, {
             "encoding" => ctx.new_readonly_getset("encoding", make_arg_getter(0)),
             "object" => ctx.new_readonly_getset("object", make_arg_getter(1)),
diff --git a/vm/src/stdlib/os.rs b/vm/src/stdlib/os.rs
index 5f83ea1a0..fe9ca465a 100644
--- a/vm/src/stdlib/os.rs
+++ b/vm/src/stdlib/os.rs
@@ -191,17 +191,16 @@ impl IntoPyException for &'_ io::Error {
                 _ => vm.ctx.exceptions.os_error.clone(),
             },
         };
-        let os_error = vm.new_exception_msg(exc_type, self.to_string());
         let errno = self.raw_os_error().into_pyobject(vm);
-        vm.set_attr(os_error.as_object(), "errno", errno).unwrap();
-        os_error
+        let msg = vm.ctx.new_str(self.to_string());
+        vm.new_exception(exc_type, vec![errno, msg])
     }
 }
 
 #[cfg(unix)]
 impl IntoPyException for nix::Error {
     fn into_pyexception(self, vm: &VirtualMachine) -> PyBaseExceptionRef {
-        let nix_error = match self {
+        match self {
             nix::Error::InvalidPath => {
                 let exc_type = vm.ctx.exceptions.file_not_found_error.clone();
                 vm.new_exception_msg(exc_type, self.to_string())
@@ -213,16 +212,15 @@ impl IntoPyException for nix::Error {
             nix::Error::UnsupportedOperation => vm.new_runtime_error(self.to_string()),
             nix::Error::Sys(errno) => {
                 let exc_type = posix::convert_nix_errno(vm, errno);
-                vm.new_exception_msg(exc_type, self.to_string())
+                vm.new_exception(
+                    exc_type,
+                    vec![
+                        vm.ctx.new_int(errno as i32),
+                        vm.ctx.new_str(self.to_string()),
+                    ],
+                )
             }
-        };
-
-        if let nix::Error::Sys(errno) = self {
-            vm.set_attr(nix_error.as_object(), "errno", vm.ctx.new_int(errno as i32))
-                .unwrap();
         }
-
-        nix_error
     }
 }