diff --git a/src/lib.rs b/src/lib.rs
index e25ae3a27d1e..e4a389427c52 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -233,6 +233,7 @@ impl<'a, 'mir, 'tcx> Machine<'a, 'mir, 'tcx> for Evaluator<'tcx> {
     type MemoryKinds = MiriMemoryKind;
 
     const MUT_STATIC_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::MutStatic);
+    const ENFORCE_VALIDITY: bool = false; // this is still WIP
 
     /// Returns Ok() when the function was handled, fail otherwise
     fn find_fn(
diff --git a/src/operator.rs b/src/operator.rs
index cf416c44c11f..13532764c973 100644
--- a/src/operator.rs
+++ b/src/operator.rs
@@ -142,8 +142,8 @@ fn ptr_eq(
                     // allocations sit right next to each other.  The C/C++ standards are
                     // somewhat fuzzy about this case, so I think for now this check is
                     // "good enough".
-                    self.memory.check_bounds(left, false)?;
-                    self.memory.check_bounds(right, false)?;
+                    self.memory.check_bounds_ptr(left, false)?;
+                    self.memory.check_bounds_ptr(right, false)?;
                     // Two live in-bounds pointers, we can compare across allocations
                     left == right
                 }
@@ -296,9 +296,9 @@ fn pointer_offset_inbounds(
         if let Scalar::Ptr(ptr) = ptr {
             // Both old and new pointer must be in-bounds.
             // (Of the same allocation, but that part is trivial with our representation.)
-            self.memory.check_bounds(ptr, false)?;
+            self.memory.check_bounds_ptr(ptr, false)?;
             let ptr = ptr.signed_offset(offset, self)?;
-            self.memory.check_bounds(ptr, false)?;
+            self.memory.check_bounds_ptr(ptr, false)?;
             Ok(Scalar::Ptr(ptr))
         } else {
             // An integer pointer. They can move around freely, as long as they do not overflow
diff --git a/tests/compile-fail/cast_fn_ptr5.rs b/tests/compile-fail/cast_fn_ptr5.rs
new file mode 100644
index 000000000000..e4ac95e67676
--- /dev/null
+++ b/tests/compile-fail/cast_fn_ptr5.rs
@@ -0,0 +1,9 @@
+fn main() {
+    fn f() -> u32 { 42 }
+
+    let g = unsafe {
+        std::mem::transmute::<fn() -> u32, fn()>(f)
+    };
+
+    g() //~ ERROR tried to call a function with return type u32 passing return place of type ()
+}