diff --git a/gc/mmtk/Cargo.lock b/gc/mmtk/Cargo.lock
index 237a5e1..b68a682 100644
--- a/gc/mmtk/Cargo.lock
+++ b/gc/mmtk/Cargo.lock
@@ -440,8 +440,8 @@ checksum = "6b947ae49db0d222b1dbc6b113ce7248a3fc3a6ca21b696717bfc000ba4484d8"
 
 [[package]]
 name = "mmtk"
-version = "0.32.0"
-source = "git+https://github.com/mmtk/mmtk-core.git?rev=8f806d56469c1c706fd1f88b757c33620bae85ba#8f806d56469c1c706fd1f88b757c33620bae85ba"
+version = "0.33.0"
+source = "git+https://github.com/mmtk/mmtk-core.git?rev=0fc014f8d05db7fcb6f49ebe20ddd43a3fe2abdf#0fc014f8d05db7fcb6f49ebe20ddd43a3fe2abdf"
 dependencies = [
  "atomic",
  "atomic-traits",
@@ -475,8 +475,8 @@ dependencies = [
 
 [[package]]
 name = "mmtk-macros"
-version = "0.32.0"
-source = "git+https://github.com/mmtk/mmtk-core.git?rev=8f806d56469c1c706fd1f88b757c33620bae85ba#8f806d56469c1c706fd1f88b757c33620bae85ba"
+version = "0.33.0"
+source = "git+https://github.com/mmtk/mmtk-core.git?rev=0fc014f8d05db7fcb6f49ebe20ddd43a3fe2abdf#0fc014f8d05db7fcb6f49ebe20ddd43a3fe2abdf"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
diff --git a/gc/mmtk/Cargo.toml b/gc/mmtk/Cargo.toml
index f274935..6f24036 100644
--- a/gc/mmtk/Cargo.toml
+++ b/gc/mmtk/Cargo.toml
@@ -25,7 +25,7 @@ features = ["vo_bit", "object_pinning", "sticky_immix_non_moving_nursery"]
 
 # Uncomment the following lines to use mmtk-core from the official repository.
 git = "https://github.com/mmtk/mmtk-core.git"
-rev = "8f806d56469c1c706fd1f88b757c33620bae85ba"
+rev = "0fc014f8d05db7fcb6f49ebe20ddd43a3fe2abdf"
 
 # Uncomment the following line to use mmtk-core from a local repository.
 # path = "../../../mmtk-core"
diff --git a/gc/mmtk/src/object_model.rs b/gc/mmtk/src/object_model.rs
index d673ca1..6dcc520 100644
--- a/gc/mmtk/src/object_model.rs
+++ b/gc/mmtk/src/object_model.rs
@@ -19,6 +19,8 @@ impl VMObjectModel {
 }
 
 impl ObjectModel<Ruby> for VMObjectModel {
+    const GLOBAL_FIELD_UNLOG_BIT_SPEC: VMGlobalFieldUnlogBitSpec =
+        VMGlobalFieldUnlogBitSpec::side_first();
     const GLOBAL_LOG_BIT_SPEC: VMGlobalLogBitSpec = VMGlobalLogBitSpec::side_first();
 
     // We overwrite the prepended word which were used to hold object sizes.
@@ -78,6 +80,14 @@ impl ObjectModel<Ruby> for VMObjectModel {
         to_obj
     }
 
+    fn try_copy(
+        from: ObjectReference,
+        semantics: CopySemantics,
+        copy_context: &mut GCWorkerCopyContext<Ruby>,
+    ) -> Option<ObjectReference> {
+        Some(Self::copy(from, semantics, copy_context))
+    }
+
     fn copy_to(_from: ObjectReference, _to: ObjectReference, _region: Address) -> Address {
         unimplemented!(
             "This function cannot be called because we do not support MarkCompact for Ruby."
diff --git a/gc/mmtk/src/scanning.rs b/gc/mmtk/src/scanning.rs
index 355a2e7..34314ab 100644
--- a/gc/mmtk/src/scanning.rs
+++ b/gc/mmtk/src/scanning.rs
@@ -25,10 +25,10 @@ impl Scanning<Ruby> for VMScanning {
         false
     }
 
-    fn scan_object<EV: SlotVisitor<RubySlot>>(
+    fn scan_object(
         _tls: VMWorkerThread,
         _object: ObjectReference,
-        _slot_visitor: &mut EV,
+        _slot_visitor: &mut impl SlotVisitor<RubySlot>,
     ) {
         unreachable!("We have not enabled slot enqueuing for any types, yet.");
     }