diff --git a/mmtk/Cargo.lock b/mmtk/Cargo.lock
index 496de72e..7d5bce2d 100644
--- a/mmtk/Cargo.lock
+++ b/mmtk/Cargo.lock
@@ -383,7 +383,7 @@ dependencies = [
 [[package]]
 name = "mmtk"
 version = "0.20.0"
-source = "git+https://github.com/mmtk/mmtk-core.git?rev=57af17fbfd94ff0df2cd3b1e504abe299ce4f0ab#57af17fbfd94ff0df2cd3b1e504abe299ce4f0ab"
+source = "git+https://github.com/mmtk/mmtk-core.git?rev=b4f45195e09e38c6deae8605c0f61eb0b534ff20#b4f45195e09e38c6deae8605c0f61eb0b534ff20"
 dependencies = [
  "atomic",
  "atomic-traits",
@@ -417,7 +417,7 @@ dependencies = [
 [[package]]
 name = "mmtk-macros"
 version = "0.20.0"
-source = "git+https://github.com/mmtk/mmtk-core.git?rev=57af17fbfd94ff0df2cd3b1e504abe299ce4f0ab#57af17fbfd94ff0df2cd3b1e504abe299ce4f0ab"
+source = "git+https://github.com/mmtk/mmtk-core.git?rev=b4f45195e09e38c6deae8605c0f61eb0b534ff20#b4f45195e09e38c6deae8605c0f61eb0b534ff20"
 dependencies = [
  "proc-macro-error",
  "proc-macro2",
@@ -477,9 +477,9 @@ checksum = "9b2a4787296e9989611394c33f193f676704af1686e70b8f8033ab5ba9a35a94"
 
 [[package]]
 name = "pest"
-version = "2.7.4"
+version = "2.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c022f1e7b65d6a24c0dbbd5fb344c66881bc01f3e5ae74a1c8100f2f985d98a4"
+checksum = "ae9cee2a55a544be8b89dc6848072af97a20f2422603c10865be2a42b580fff5"
 dependencies = [
  "memchr",
  "thiserror",
diff --git a/mmtk/Cargo.toml b/mmtk/Cargo.toml
index a14b32cd..8ab15f97 100644
--- a/mmtk/Cargo.toml
+++ b/mmtk/Cargo.toml
@@ -28,7 +28,7 @@ log = {version = "0.4", features = ["max_level_trace", "release_max_level_off"]
 # - change branch/rev
 # - change repo name
 # But other changes including adding/removing whitespaces in commented lines may break the CI.
-mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "57af17fbfd94ff0df2cd3b1e504abe299ce4f0ab" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "b4f45195e09e38c6deae8605c0f61eb0b534ff20" }
 # Uncomment the following to build locally - if you change the path locally, do not commit the change in a PR
 # mmtk = { path = "../repos/mmtk-core" }
 
diff --git a/mmtk/src/scanning.rs b/mmtk/src/scanning.rs
index 2620ff9a..3b8a1644 100644
--- a/mmtk/src/scanning.rs
+++ b/mmtk/src/scanning.rs
@@ -21,6 +21,7 @@ use mmtk::vm::ActivePlan;
 use mmtk::vm::EdgeVisitor;
 use mmtk::vm::RootsWorkFactory;
 use mmtk::vm::Scanning;
+use mmtk::MMTK;
 use mmtk::*;
 use object_model::VMObjectModel;
 use std::mem;
@@ -227,7 +228,7 @@ where
         .generational()
         .map_or(false, |plan| plan.is_current_gc_nursery());
 
-    let need_retain = SINGLETON.get_plan().is_emergency_collection();
+    let need_retain = SINGLETON.is_emergency_collection();
 
     tracer_context.with_tracer(worker, |tracer| unsafe {
         let scan_result = jtoc_call!(