diff --git a/vm/src/stdlib/nt.rs b/vm/src/stdlib/nt.rs
index 9fa69291f..1b2dd55e9 100644
--- a/vm/src/stdlib/nt.rs
+++ b/vm/src/stdlib/nt.rs
@@ -16,8 +16,7 @@ pub(crate) mod module {
         builtins::{PyDictRef, PyStrRef, PyTupleRef},
         common::{crt_fd::Fd, os::last_os_error, suppress_iph},
         convert::ToPyException,
-        function::Either,
-        function::OptionalArg,
+        function::{Either, OptionalArg},
         ospath::OsPath,
         stdlib::os::{errno_err, DirFd, FollowSymlinks, SupportFunc, TargetIsDirectory, _os},
         PyResult, TryFromObject, VirtualMachine,
diff --git a/vm/src/stdlib/os.rs b/vm/src/stdlib/os.rs
index 040429e8e..bb2f6808e 100644
--- a/vm/src/stdlib/os.rs
+++ b/vm/src/stdlib/os.rs
@@ -407,7 +407,7 @@ pub(super) mod _os {
             return Err(vm.new_value_error("embedded null byte".to_string()));
         }
         if key.is_empty() || key.contains('=') {
-            return Err(vm.new_value_error("illegal environment variable name".to_string()));
+            return Err(vm.new_errno_error(22, "Invalid argument".to_owned()));
         }
         env::remove_var(key);
         Ok(())
diff --git a/vm/src/vm/vm_new.rs b/vm/src/vm/vm_new.rs
index 922c137a0..4677d196f 100644
--- a/vm/src/vm/vm_new.rs
+++ b/vm/src/vm/vm_new.rs
@@ -189,6 +189,15 @@ impl VirtualMachine {
         self.new_exception_msg(os_error, msg)
     }
 
+    pub fn new_errno_error(&self, errno: i32, msg: String) -> PyBaseExceptionRef {
+        let vm = self;
+        let exc_type =
+            crate::exceptions::errno_to_exc_type(errno, vm).unwrap_or(vm.ctx.exceptions.os_error);
+
+        let errno_obj = vm.new_pyobj(errno);
+        vm.new_exception(exc_type.to_owned(), vec![errno_obj, vm.new_pyobj(msg)])
+    }
+
     pub fn new_system_error(&self, msg: String) -> PyBaseExceptionRef {
         let sys_error = self.ctx.exceptions.system_error.to_owned();
         self.new_exception_msg(sys_error, msg)