diff --git a/gc/mmtk/src/api.rs b/gc/mmtk/src/api.rs
index a1b94d520d..5ec39729c3 100644
--- a/gc/mmtk/src/api.rs
+++ b/gc/mmtk/src/api.rs
@@ -108,8 +108,7 @@ pub extern "C" fn mmtk_builder_default() -> *mut MMTKBuilder {
         if !builder.options.threads.set(threads) {
             // MMTk will validate it and reject 0.
             eprintln!(
-                "[FATAL] Failed to set the number of MMTk threads to {}",
-                threads
+                "[FATAL] Failed to set the number of MMTk threads to {threads}"
             );
             std::process::exit(1);
         }
@@ -121,8 +120,7 @@ pub extern "C" fn mmtk_builder_default() -> *mut MMTKBuilder {
 
     if heap_min >= heap_max {
         eprintln!(
-            "[FATAL] MMTK_HEAP_MIN({}) >= MMTK_HEAP_MAX({})",
-            heap_min, heap_max
+            "[FATAL] MMTK_HEAP_MIN({heap_min}) >= MMTK_HEAP_MAX({heap_max})"
         );
         std::process::exit(1);
     }
diff --git a/gc/mmtk/src/binding.rs b/gc/mmtk/src/binding.rs
index 619b7f246c..811cbf8abf 100644
--- a/gc/mmtk/src/binding.rs
+++ b/gc/mmtk/src/binding.rs
@@ -119,7 +119,7 @@ impl RubyBinding {
     }
 
     pub fn register_wb_unprotected_object(&self, object: ObjectReference) {
-        debug!("Registering WB-unprotected object: {}", object);
+        debug!("Registering WB-unprotected object: {object}");
         let mut objects = self.wb_unprotected_objects.lock().unwrap();
         objects.insert(object);
     }
diff --git a/gc/mmtk/src/collection.rs b/gc/mmtk/src/collection.rs
index 0570b64e3a..34d5f45696 100644
--- a/gc/mmtk/src/collection.rs
+++ b/gc/mmtk/src/collection.rs
@@ -42,8 +42,7 @@ impl Collection<Ruby> for VMCollection {
                 .spawn(move || {
                     let ordinal = worker.ordinal;
                     debug!(
-                        "Hello! This is MMTk Worker Thread running! ordinal: {}",
-                        ordinal
+                        "Hello! This is MMTk Worker Thread running! ordinal: {ordinal}"
                     );
                     crate::register_gc_thread(thread::current().id());
                     let ptr_worker = &mut *worker as *mut GCWorker<Ruby>;
@@ -56,8 +55,7 @@ impl Collection<Ruby> for VMCollection {
                         worker,
                     );
                     debug!(
-                        "An MMTk Worker Thread is quitting. Good bye! ordinal: {}",
-                        ordinal
+                        "An MMTk Worker Thread is quitting. Good bye! ordinal: {ordinal}"
                     );
                     crate::unregister_gc_thread(thread::current().id());
                 })
diff --git a/gc/mmtk/src/scanning.rs b/gc/mmtk/src/scanning.rs
index 36c0f998f4..66697ea565 100644
--- a/gc/mmtk/src/scanning.rs
+++ b/gc/mmtk/src/scanning.rs
@@ -48,9 +48,7 @@ impl Scanning<Ruby> for VMScanning {
             let forwarded_target = object_tracer.trace_object(target_object);
             if forwarded_target != target_object {
                 trace!(
-                    "  Forwarded target {} -> {}",
-                    target_object,
-                    forwarded_target
+                    "  Forwarded target {target_object} -> {forwarded_target}"
                 );
             }
             forwarded_target
@@ -252,14 +250,12 @@ impl<F: RootsWorkFactory<RubySlot>> GCWork<Ruby> for ScanWbUnprotectedRoots<F> {
             for object in self.objects.iter().copied() {
                 if object.is_reachable() {
                     debug!(
-                        "[wb_unprot_roots] Visiting WB-unprotected object (parent): {}",
-                        object
+                        "[wb_unprot_roots] Visiting WB-unprotected object (parent): {object}"
                     );
                     (upcalls().scan_object_ruby_style)(object);
                 } else {
                     debug!(
-                        "[wb_unprot_roots] Skipping young WB-unprotected object (parent): {}",
-                        object
+                        "[wb_unprot_roots] Skipping young WB-unprotected object (parent): {object}"
                     );
                 }
             }
diff --git a/gc/mmtk/src/weak_proc.rs b/gc/mmtk/src/weak_proc.rs
index 204dd203aa..98f8c5abea 100644
--- a/gc/mmtk/src/weak_proc.rs
+++ b/gc/mmtk/src/weak_proc.rs
@@ -103,7 +103,7 @@ impl GCWork<Ruby> for ProcessObjFreeCandidates {
 
         let n_cands = obj_free_candidates.len();
 
-        debug!("Total: {} candidates", n_cands);
+        debug!("Total: {n_cands} candidates");
 
         // Process obj_free
         let mut new_candidates = Vec::new();
@@ -113,9 +113,7 @@ impl GCWork<Ruby> for ProcessObjFreeCandidates {
                 // Forward and add back to the candidate list.
                 let new_object = object.forward();
                 trace!(
-                    "Forwarding obj_free candidate: {} -> {}",
-                    object,
-                    new_object
+                    "Forwarding obj_free candidate: {object} -> {new_object}"
                 );
                 new_candidates.push(new_object);
             } else {
@@ -158,11 +156,10 @@ trait GlobalTableProcessingWork {
         let forward_object = |_worker, object: ObjectReference, _pin| {
             debug_assert!(
                 mmtk::memory_manager::is_mmtk_object(object.to_raw_address()).is_some(),
-                "{} is not an MMTk object",
-                object
+                "{object} is not an MMTk object"
             );
             let result = object.forward();
-            trace!("Forwarding reference: {} -> {}", object, result);
+            trace!("Forwarding reference: {object} -> {result}");
             result
         };
 
@@ -217,13 +214,11 @@ impl GCWork<Ruby> for UpdateWbUnprotectedObjectsList {
                 // Forward and add back to the candidate list.
                 let new_object = object.forward();
                 trace!(
-                    "Forwarding WB-unprotected object: {} -> {}",
-                    object,
-                    new_object
+                    "Forwarding WB-unprotected object: {object} -> {new_object}"
                 );
                 objects.insert(new_object);
             } else {
-                trace!("Removing WB-unprotected object from list: {}", object);
+                trace!("Removing WB-unprotected object from list: {object}");
             }
         }