diff --git a/runtime/vm/clustered_snapshot.cc b/runtime/vm/clustered_snapshot.cc
index a67ace8dee9..42df2954a5e 100644
--- a/runtime/vm/clustered_snapshot.cc
+++ b/runtime/vm/clustered_snapshot.cc
@@ -1437,7 +1437,7 @@ class FieldDeserializationCluster : public DeserializationCluster {
         field.set_guarded_list_length_unsafe(Field::kNoFixedLength);
         field.set_guarded_list_length_in_object_offset_unsafe(
             Field::kUnknownLengthOffset);
-        field.set_static_type_exactness_state(
+        field.set_static_type_exactness_state_unsafe(
             StaticTypeExactnessState::NotTracking());
       }
     } else {
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index ea59e19cac1..99c29570f42 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -10635,7 +10635,7 @@ void Field::InitializeNew(const Field& result,
   result.set_initializer_changed_after_initialization(false);
   NOT_IN_PRECOMPILED(result.set_kernel_offset(0));
   result.set_has_pragma(false);
-  result.set_static_type_exactness_state(
+  result.set_static_type_exactness_state_unsafe(
       StaticTypeExactnessState::NotTracking());
   auto isolate_group = IsolateGroup::Current();
 
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 786fcb643a7..f2e14f43322 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -4145,11 +4145,20 @@ class Field : public Object {
 
   StaticTypeExactnessState static_type_exactness_state() const {
     return StaticTypeExactnessState::Decode(
-        untag()->static_type_exactness_state_);
+        LoadNonPointer<int8_t, std::memory_order_relaxed>(
+            &untag()->static_type_exactness_state_));
   }
 
   void set_static_type_exactness_state(StaticTypeExactnessState state) const {
-    StoreNonPointer(&untag()->static_type_exactness_state_, state.Encode());
+    DEBUG_ASSERT(
+        IsolateGroup::Current()->program_lock()->IsCurrentThreadWriter());
+    set_static_type_exactness_state_unsafe(state);
+  }
+
+  void set_static_type_exactness_state_unsafe(
+      StaticTypeExactnessState state) const {
+    StoreNonPointer<int8_t, int8_t, std::memory_order_relaxed>(
+        &untag()->static_type_exactness_state_, state.Encode());
   }
 
   static intptr_t static_type_exactness_state_offset() {