diff --git a/src/tools/miri/src/shims/unix/sync.rs b/src/tools/miri/src/shims/unix/sync.rs
index 544f3259eeaf..9c096760415e 100644
--- a/src/tools/miri/src/shims/unix/sync.rs
+++ b/src/tools/miri/src/shims/unix/sync.rs
@@ -727,6 +727,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, Scalar<Provenance>> {
         let this = self.eval_context_mut();
 
+        // Does not exist on macOS!
+        if !matches!(&*this.tcx.sess.target.os, "linux") {
+            throw_unsup_format!(
+                "`pthread_condattr_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let clock_id = this.read_scalar(clock_id_op)?.to_i32()?;
         if clock_id == this.eval_libc_i32("CLOCK_REALTIME")
             || clock_id == this.eval_libc_i32("CLOCK_MONOTONIC")
@@ -747,6 +755,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, Scalar<Provenance>> {
         let this = self.eval_context_mut();
 
+        // Does not exist on macOS!
+        if !matches!(&*this.tcx.sess.target.os, "linux") {
+            throw_unsup_format!(
+                "`pthread_condattr_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let clock_id = condattr_get_clock_id(this, attr_op)?;
         this.write_scalar(Scalar::from_i32(clock_id), &this.deref_pointer(clk_id_op)?)?;
 
diff --git a/src/tools/miri/tests/pass-dep/shims/libc-rsfs.stdout b/src/tools/miri/tests/pass-dep/shims/libc-rsfs.stdout
deleted file mode 100644
index b6fa69e3d5d2..000000000000
--- a/src/tools/miri/tests/pass-dep/shims/libc-rsfs.stdout
+++ /dev/null
@@ -1 +0,0 @@
-hello dup fd
diff --git a/src/tools/miri/tests/pass-dep/shims/pthread-sync.rs b/src/tools/miri/tests/pass-dep/shims/pthread-sync.rs
index c9d10cb83d4d..12d3f2b6f142 100644
--- a/src/tools/miri/tests/pass-dep/shims/pthread-sync.rs
+++ b/src/tools/miri/tests/pass-dep/shims/pthread-sync.rs
@@ -19,6 +19,7 @@ fn main() {
     check_rwlock_write();
     check_rwlock_read_no_deadlock();
     check_cond();
+    check_condattr();
 }
 
 fn test_mutex_libc_init_recursive() {
@@ -261,6 +262,31 @@ fn check_cond() {
     }
 }
 
+fn check_condattr() {
+    unsafe {
+        // Just smoke-testing that these functions can be called.
+        let mut attr: MaybeUninit<libc::pthread_condattr_t> = MaybeUninit::uninit();
+        assert_eq!(libc::pthread_condattr_init(attr.as_mut_ptr()), 0);
+
+        #[cfg(not(target_os = "macos"))] // setclock-getclock do not exist on macOS
+        {
+            let clock_id = libc::CLOCK_MONOTONIC;
+            assert_eq!(libc::pthread_condattr_setclock(attr.as_mut_ptr(), clock_id), 0);
+            let mut check_clock_id = MaybeUninit::<libc::clockid_t>::uninit();
+            assert_eq!(
+                libc::pthread_condattr_getclock(attr.as_mut_ptr(), check_clock_id.as_mut_ptr()),
+                0
+            );
+            assert_eq!(check_clock_id.assume_init(), clock_id);
+        }
+
+        let mut cond: MaybeUninit<libc::pthread_cond_t> = MaybeUninit::uninit();
+        assert_eq!(libc::pthread_cond_init(cond.as_mut_ptr(), attr.as_ptr()), 0);
+        assert_eq!(libc::pthread_condattr_destroy(attr.as_mut_ptr()), 0);
+        assert_eq!(libc::pthread_cond_destroy(cond.as_mut_ptr()), 0);
+    }
+}
+
 // std::sync::RwLock does not even used pthread_rwlock any more.
 // Do some smoke testing of the API surface.
 fn test_rwlock_libc_static_initializer() {