diff --git a/example/mini_core.rs b/example/mini_core.rs
index 67a0d0dabea..39988cf64e5 100644
--- a/example/mini_core.rs
+++ b/example/mini_core.rs
@@ -8,6 +8,7 @@
     rustc_attrs,
     transparent_unions,
     auto_traits,
+    freeze_impls,
     thread_local
 )]
 #![no_core]
diff --git a/src/base.rs b/src/base.rs
index 1ce920f3bdb..2415c2c90b2 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -779,7 +779,7 @@ fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
                         NullOp::OffsetOf(fields) => {
                             layout.offset_of_subfield(fx, fields.iter()).bytes()
                         }
-                        NullOp::DebugAssertions => {
+                        NullOp::UbCheck(_) => {
                             let val = fx.tcx.sess.opts.debug_assertions;
                             let val = CValue::by_val(
                                 fx.bcx.ins().iconst(types::I8, i64::try_from(val).unwrap()),
diff --git a/src/constant.rs b/src/constant.rs
index 18c5960ffc6..cec479218b7 100644
--- a/src/constant.rs
+++ b/src/constant.rs
@@ -71,7 +71,7 @@ pub(crate) fn eval_mir_constant<'tcx>(
     // This cannot fail because we checked all required_consts in advance.
     let val = cv
         .eval(fx.tcx, ty::ParamEnv::reveal_all(), Some(constant.span))
-        .expect("erroneous constant not captured by required_consts");
+        .expect("erroneous constant missed by mono item collection");
     (val, cv.ty())
 }
 
diff --git a/src/main_shim.rs b/src/main_shim.rs
index 6535c3a367b..1abfded8b11 100644
--- a/src/main_shim.rs
+++ b/src/main_shim.rs
@@ -115,14 +115,12 @@ fn create_entry_fn(
                         termination_trait,
                     )
                     .unwrap();
-                let report = Instance::resolve(
+                let report = Instance::expect_resolve(
                     tcx,
                     ParamEnv::reveal_all(),
                     report.def_id,
                     tcx.mk_args(&[GenericArg::from(main_ret_ty)]),
                 )
-                .unwrap()
-                .unwrap()
                 .polymorphize(tcx);
 
                 let report_name = tcx.symbol_name(report).name;
@@ -142,14 +140,12 @@ fn create_entry_fn(
                 }
             } else if is_main_fn {
                 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
-                let start_instance = Instance::resolve(
+                let start_instance = Instance::expect_resolve(
                     tcx,
                     ParamEnv::reveal_all(),
                     start_def_id,
                     tcx.mk_args(&[main_ret_ty.into()]),
                 )
-                .unwrap()
-                .unwrap()
                 .polymorphize(tcx);
                 let start_func_id = import_function(tcx, m, start_instance);