diff --git a/src/machine.rs b/src/machine.rs
index 84ac8b81a061..73e7ce665b85 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -106,8 +106,7 @@ impl MemoryExtra {
     pub fn init_extern_statics<'tcx, 'mir>(
         this: &mut MiriEvalContext<'mir, 'tcx>,
     ) -> InterpResult<'tcx> {
-        let target_os = this.tcx.sess.target.target.target_os.as_str();
-        match target_os {
+        match this.tcx.sess.target.target.target_os.as_str() {
             "linux" => {
                 // "__cxa_thread_atexit_impl"
                 // This should be all-zero, pointer-sized.
diff --git a/src/shims/fs.rs b/src/shims/fs.rs
index 9778775fca64..b779bf165d2b 100644
--- a/src/shims/fs.rs
+++ b/src/shims/fs.rs
@@ -802,7 +802,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
         this.check_no_isolation("mkdir")?;
 
-        let _mode = if this.tcx.sess.target.target.target_os.as_str() == "macos" {
+        let _mode = if this.tcx.sess.target.target.target_os == "macos" {
             u32::from(this.read_scalar(mode_op)?.not_undef()?.to_u16()?)
         } else {
             this.read_scalar(mode_op)?.to_u32()?
diff --git a/src/shims/intrinsics.rs b/src/shims/intrinsics.rs
index 9a6bd58ba42e..91371e2c9df9 100644
--- a/src/shims/intrinsics.rs
+++ b/src/shims/intrinsics.rs
@@ -36,6 +36,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let (dest, ret) = match ret {
             None => match intrinsic_name {
                 "miri_start_panic" => return this.handle_miri_start_panic(args, unwind),
+                "unreachable" => throw_ub!(Unreachable),
                 _ => throw_unsup_format!("unimplemented (diverging) intrinsic: {}", intrinsic_name),
             },
             Some(p) => p,
diff --git a/tests/compile-fail/unreachable.rs b/tests/compile-fail/unreachable.rs
new file mode 100644
index 000000000000..245ef29cad35
--- /dev/null
+++ b/tests/compile-fail/unreachable.rs
@@ -0,0 +1,4 @@
+// error-pattern: entering unreachable code
+fn main() {
+    unsafe { std::hint::unreachable_unchecked() }
+}