diff --git a/src/tools/miri/src/shims/unix/linux/epoll.rs b/src/tools/miri/src/shims/unix/linux/epoll.rs
index f743a298dad03..de108665e9f8c 100644
--- a/src/tools/miri/src/shims/unix/linux/epoll.rs
+++ b/src/tools/miri/src/shims/unix/linux/epoll.rs
@@ -433,9 +433,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let timeout = this.read_scalar(timeout)?.to_i32()?;
 
         if epfd_value <= 0 || maxevents <= 0 {
-            this.set_last_error(LibcError("EINVAL"))?;
-            this.write_int(-1, dest)?;
-            return interp_ok(());
+            return this.set_last_error_and_return(LibcError("EINVAL"), dest);
         }
 
         // This needs to come after the maxevents value check, or else maxevents.try_into().unwrap()
diff --git a/src/tools/miri/src/shims/unix/linux/sync.rs b/src/tools/miri/src/shims/unix/linux/sync.rs
index 8640ce2e2cd6b..c258be78f7647 100644
--- a/src/tools/miri/src/shims/unix/linux/sync.rs
+++ b/src/tools/miri/src/shims/unix/linux/sync.rs
@@ -63,8 +63,7 @@ pub fn futex<'tcx>(
             };
 
             if bitset == 0 {
-                this.set_last_error(LibcError("EINVAL"))?;
-                this.write_scalar(Scalar::from_target_isize(-1, this), dest)?;
+                this.set_last_error_and_return(LibcError("EINVAL"), dest)?;
                 return interp_ok(());
             }
 
@@ -75,9 +74,7 @@ pub fn futex<'tcx>(
                 let duration = match this.read_timespec(&timeout)? {
                     Some(duration) => duration,
                     None => {
-                        this.set_last_error(LibcError("EINVAL"))?;
-                        this.write_scalar(Scalar::from_target_isize(-1, this), dest)?;
-                        return interp_ok(());
+                        return this.set_last_error_and_return(LibcError("EINVAL"), dest);
                     }
                 };
                 let timeout_clock = if op & futex_realtime == futex_realtime {
@@ -153,12 +150,12 @@ pub fn futex<'tcx>(
                     Scalar::from_target_isize(0, this), // retval_succ
                     Scalar::from_target_isize(-1, this), // retval_timeout
                     dest.clone(),
-                    this.eval_libc("ETIMEDOUT"),
+                    this.eval_libc("ETIMEDOUT"), // errno_timeout
                 );
             } else {
                 // The futex value doesn't match the expected value, so we return failure
                 // right away without sleeping: -1 and errno set to EAGAIN.
-                this.set_last_error_and_return(LibcError("EAGAIN"), dest)?;
+                return this.set_last_error_and_return(LibcError("EAGAIN"), dest);
             }
         }
         // FUTEX_WAKE: (int *addr, int op = FUTEX_WAKE, int val)
@@ -178,9 +175,7 @@ pub fn futex<'tcx>(
                 u32::MAX
             };
             if bitset == 0 {
-                this.set_last_error(LibcError("EINVAL"))?;
-                this.write_scalar(Scalar::from_target_isize(-1, this), dest)?;
-                return interp_ok(());
+                return this.set_last_error_and_return(LibcError("EINVAL"), dest);
             }
             // Together with the SeqCst fence in futex_wait, this makes sure that futex_wait
             // will see the latest value on addr which could be changed by our caller
diff --git a/src/tools/miri/src/shims/windows/sync.rs b/src/tools/miri/src/shims/windows/sync.rs
index f8861085fe5de..f7566a8112da7 100644
--- a/src/tools/miri/src/shims/windows/sync.rs
+++ b/src/tools/miri/src/shims/windows/sync.rs
@@ -202,7 +202,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 Scalar::from_i32(1), // retval_succ
                 Scalar::from_i32(0), // retval_timeout
                 dest.clone(),
-                this.eval_windows("c", "ERROR_TIMEOUT"),
+                this.eval_windows("c", "ERROR_TIMEOUT"), // errno_timeout
             );
         }