diff --git a/src/tools/miri/src/concurrency/sync.rs b/src/tools/miri/src/concurrency/sync.rs
index 76a045c4dc16..91865a2192cf 100644
--- a/src/tools/miri/src/concurrency/sync.rs
+++ b/src/tools/miri/src/concurrency/sync.rs
@@ -45,7 +45,7 @@ macro_rules! declare_id {
                 // We use 0 as a sentinel value (see the comment above) and,
                 // therefore, need to shift by one when converting from an index
                 // into a vector.
-                let shifted_idx = u32::try_from(idx).unwrap().checked_add(1).unwrap();
+                let shifted_idx = u32::try_from(idx).unwrap().strict_add(1);
                 $name(std::num::NonZero::new(shifted_idx).unwrap())
             }
             fn index(self) -> usize {
@@ -350,7 +350,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         } else {
             mutex.owner = Some(thread);
         }
-        mutex.lock_count = mutex.lock_count.checked_add(1).unwrap();
+        mutex.lock_count = mutex.lock_count.strict_add(1);
         if let Some(data_race) = &this.machine.data_race {
             data_race.acquire_clock(&mutex.clock, &this.machine.threads);
         }
@@ -370,9 +370,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 return Ok(None);
             }
             let old_lock_count = mutex.lock_count;
-            mutex.lock_count = old_lock_count
-                .checked_sub(1)
-                .expect("invariant violation: lock_count == 0 iff the thread is unlocked");
+            mutex.lock_count = old_lock_count.strict_sub(1);
             if mutex.lock_count == 0 {
                 mutex.owner = None;
                 // The mutex is completely unlocked. Try transferring ownership
@@ -450,7 +448,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         trace!("rwlock_reader_lock: {:?} now also held (one more time) by {:?}", id, thread);
         let rwlock = &mut this.machine.sync.rwlocks[id];
         let count = rwlock.readers.entry(thread).or_insert(0);
-        *count = count.checked_add(1).expect("the reader counter overflowed");
+        *count = count.strict_add(1);
         if let Some(data_race) = &this.machine.data_race {
             data_race.acquire_clock(&rwlock.clock_unlocked, &this.machine.threads);
         }
diff --git a/src/tools/miri/src/shims/os_str.rs b/src/tools/miri/src/shims/os_str.rs
index 68eca5a3a0ff..533992e35ab1 100644
--- a/src/tools/miri/src/shims/os_str.rs
+++ b/src/tools/miri/src/shims/os_str.rs
@@ -142,7 +142,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         os_str: &OsStr,
         memkind: MemoryKind,
     ) -> InterpResult<'tcx, Pointer> {
-        let size = u64::try_from(os_str.len()).unwrap().checked_add(1).unwrap(); // Make space for `0` terminator.
+        let size = u64::try_from(os_str.len()).unwrap().strict_add(1); // Make space for `0` terminator.
         let this = self.eval_context_mut();
 
         let arg_type = Ty::new_array(this.tcx.tcx, this.tcx.types.u8, size);
@@ -158,7 +158,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         os_str: &OsStr,
         memkind: MemoryKind,
     ) -> InterpResult<'tcx, Pointer> {
-        let size = u64::try_from(os_str.len()).unwrap().checked_add(1).unwrap(); // Make space for `0x0000` terminator.
+        let size = u64::try_from(os_str.len()).unwrap().strict_add(1); // Make space for `0x0000` terminator.
         let this = self.eval_context_mut();
 
         let arg_type = Ty::new_array(this.tcx.tcx, this.tcx.types.u16, size);
diff --git a/src/tools/miri/src/shims/unix/fs.rs b/src/tools/miri/src/shims/unix/fs.rs
index c8805f054ecc..262e71756c64 100644
--- a/src/tools/miri/src/shims/unix/fs.rs
+++ b/src/tools/miri/src/shims/unix/fs.rs
@@ -893,7 +893,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 
                 let dirent64_layout = this.libc_ty_layout("dirent64");
                 let d_name_offset = dirent64_layout.fields.offset(4 /* d_name */).bytes();
-                let size = d_name_offset.checked_add(name_len).unwrap();
+                let size = d_name_offset.strict_add(name_len);
 
                 let entry = this.allocate_ptr(
                     Size::from_bytes(size),
@@ -994,7 +994,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     name_place.ptr(),
                     name_place.layout.size.bytes(),
                 )?;
-                let file_name_len = file_name_buf_len.checked_sub(1).unwrap();
+                let file_name_len = file_name_buf_len.strict_sub(1);
                 if !name_fits {
                     throw_unsup_format!(
                         "a directory entry had a name too large to fit in libc::dirent"
diff --git a/src/tools/miri/src/shims/x86/avx.rs b/src/tools/miri/src/shims/x86/avx.rs
index 07d737e06635..0d2977b7b6fe 100644
--- a/src/tools/miri/src/shims/x86/avx.rs
+++ b/src/tools/miri/src/shims/x86/avx.rs
@@ -176,8 +176,7 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     // of 4.
                     let chunk_base = i & !0b11;
                     let src_i = u64::from(this.read_scalar(&control)?.to_u32()? & 0b11)
-                        .checked_add(chunk_base)
-                        .unwrap();
+                        .strict_add(chunk_base);
 
                     this.copy_op(
                         &this.project_index(&data, src_i)?,
@@ -210,9 +209,8 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     // second instead of the first, ask Intel). To read the value from the current
                     // chunk, add the destination index truncated to a multiple of 2.
                     let chunk_base = i & !1;
-                    let src_i = ((this.read_scalar(&control)?.to_u64()? >> 1) & 1)
-                        .checked_add(chunk_base)
-                        .unwrap();
+                    let src_i =
+                        ((this.read_scalar(&control)?.to_u64()? >> 1) & 1).strict_add(chunk_base);
 
                     this.copy_op(
                         &this.project_index(&data, src_i)?,