diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index 1603ba96c3..836923f31a 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -562,11 +562,11 @@ int Heap::GetNextTemplateSerialNumber() {
 
 AlwaysAllocateScope::AlwaysAllocateScope(Isolate* isolate)
     : heap_(isolate->heap()) {
-  heap_->always_allocate_scope_count_.Increment(1);
+  heap_->always_allocate_scope_count_++;
 }
 
 AlwaysAllocateScope::~AlwaysAllocateScope() {
-  heap_->always_allocate_scope_count_.Decrement(1);
+  heap_->always_allocate_scope_count_--;
 }
 
 CodeSpaceMemoryModificationScope::CodeSpaceMemoryModificationScope(Heap* heap)
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 3c502035ad..dba657563f 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -141,6 +141,7 @@ Heap::Heap()
     : external_memory_(0),
       external_memory_limit_(kExternalAllocationSoftLimit),
       external_memory_at_last_mark_compact_(0),
+      external_memory_concurrently_freed_(0),
       isolate_(nullptr),
       code_range_size_(0),
       // semispace_size_ should be a power of 2 and old_generation_size_ should
diff --git a/src/heap/heap.h b/src/heap/heap.h
index ef1499ecd9..d0d325f49e 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -936,12 +936,12 @@ class Heap {
   void update_external_memory(int64_t delta) { external_memory_ += delta; }
 
   void update_external_memory_concurrently_freed(intptr_t freed) {
-    external_memory_concurrently_freed_.Increment(freed);
+    external_memory_concurrently_freed_ += freed;
   }
 
   void account_external_memory_concurrently_freed() {
-    external_memory_ -= external_memory_concurrently_freed_.Value();
-    external_memory_concurrently_freed_.SetValue(0);
+    external_memory_ -= external_memory_concurrently_freed_;
+    external_memory_concurrently_freed_ = 0;
   }
 
   void CompactFixedArraysOfWeakCells();
@@ -2113,7 +2113,7 @@ class Heap {
     return old_generation_allocation_limit_;
   }
 
-  bool always_allocate() { return always_allocate_scope_count_.Value() != 0; }
+  bool always_allocate() { return always_allocate_scope_count_ != 0; }
 
   bool CanExpandOldGeneration(size_t size);
 
@@ -2220,7 +2220,7 @@ class Heap {
   int64_t external_memory_at_last_mark_compact_;
 
   // The amount of memory that has been freed concurrently.
-  base::AtomicNumber<intptr_t> external_memory_concurrently_freed_;
+  std::atomic<intptr_t> external_memory_concurrently_freed_;
 
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.
@@ -2253,7 +2253,7 @@ class Heap {
 
   // This is not the depth of nested AlwaysAllocateScope's but rather a single
   // count, as scopes can be acquired from multiple tasks (read: threads).
-  base::AtomicNumber<size_t> always_allocate_scope_count_;
+  std::atomic<size_t> always_allocate_scope_count_;
 
   // Stores the memory pressure level that set by MemoryPressureNotification
   // and reset by a mark-compact garbage collection.