diff --git a/rust-version b/rust-version
index d8673b921164..37be5591da6e 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-7bdb5dee7bac15458b10b148e9e24968e633053e
+a3bc0e752fad96f537b73f4e9bc805a73d404f7b
diff --git a/tests/compile-fail/generator-pinned-moved.rs b/tests/compile-fail/generator-pinned-moved.rs
index 8f873f37a5f8..e0ce5cb7333a 100644
--- a/tests/compile-fail/generator-pinned-moved.rs
+++ b/tests/compile-fail/generator-pinned-moved.rs
@@ -34,10 +34,10 @@ where
 
 fn main() {
     let mut generator_iterator_2 = {
-        let mut generator_iterator = GeneratorIteratorAdapter(firstn());
+        let mut generator_iterator = Box::new(GeneratorIteratorAdapter(firstn()));
         generator_iterator.next(); // pin it
 
-        generator_iterator // move it
+        Box::new(*generator_iterator) // move it
     }; // *deallocate* generator_iterator
 
     generator_iterator_2.next(); // and use moved value
diff --git a/tests/compile-fail/storage_dead_dangling.rs b/tests/compile-fail/storage_dead_dangling.rs
index bf2503917ccb..ad8e05537e1a 100644
--- a/tests/compile-fail/storage_dead_dangling.rs
+++ b/tests/compile-fail/storage_dead_dangling.rs
@@ -1,5 +1,5 @@
-// This should fail even without validation
-// compile-flags: -Zmiri-disable-validation
+// This should fail even without validation, but some MIR opts mask the error
+// compile-flags: -Zmiri-disable-validation -Zmir-opt-level=0
 
 static mut LEAK: usize = 0;
 
diff --git a/tests/compile-fail/validity/transmute_through_ptr.rs b/tests/compile-fail/validity/transmute_through_ptr.rs
index 6a88fdaea1ee..0ef69efb86e6 100644
--- a/tests/compile-fail/validity/transmute_through_ptr.rs
+++ b/tests/compile-fail/validity/transmute_through_ptr.rs
@@ -1,4 +1,5 @@
 #[repr(u32)]
+#[derive(Debug)]
 enum Bool { True }
 
 fn evil(x: &mut Bool) {
@@ -9,6 +10,7 @@ fn evil(x: &mut Bool) {
 fn main() {
     let mut x = Bool::True;
     evil(&mut x);
-    let _y = x; // reading this ought to be enough to trigger validation
+    let y = x; // reading this ought to be enough to trigger validation
     //~^ ERROR encountered 0x0000002c at .<enum-tag>, but expected a valid enum tag
+    println!("{:?}", y); // make sure it is used (and not optimized away)
 }