diff --git a/src/shims/unix/fs.rs b/src/shims/unix/fs.rs
index 7d60273232..bf99412af6 100644
--- a/src/shims/unix/fs.rs
+++ b/src/shims/unix/fs.rs
@@ -605,7 +605,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             // (Technically we do not support *not* setting this flag, but we ignore that.)
             mirror |= o_cloexec;
         }
-        if cfg!(target_os = "linux") {
+        if this.tcx.sess.target.os == "linux" {
             let o_tmpfile = this.eval_libc_i32("O_TMPFILE")?;
             if flag & o_tmpfile != 0 {
                 // if the flag contains `O_TMPFILE` then we return a graceful error