diff --git a/src/heap.cc b/src/heap.cc
index eb15f91..6228fcc 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -156,10 +156,6 @@
   return obj;
 }
 
-void Heap::WriteBarrier(const Object* obj) {
-  // TODO: mark obj's card.
-}
-
 bool Heap::IsHeapAddress(const Object* obj) {
   // Note: we deliberately don't take the lock here, and mustn't test anything that would
   // require taking the lock.
diff --git a/src/heap.h b/src/heap.h
index 773789b..1c2b7c9 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -139,7 +139,9 @@
 
   // Must be called if a field of an Object in the heap changes, and before any GC safe-point.
   // The call is not needed if NULL is stored in the field.
-  static void WriteBarrier(const Object* object);
+  static void WriteBarrier(const Object* object) {
+    // TODO: re-enable card marking when concurrent collector is active.
+  }
 
  private:
   // Allocates uninitialized storage.
diff --git a/src/java_lang_System.cc b/src/java_lang_System.cc
index 2bb767d..398eeb9 100644
--- a/src/java_lang_System.cc
+++ b/src/java_lang_System.cc
@@ -187,8 +187,7 @@
   if (sameDimensions && srcComponentType->InstanceOf(dstComponentType)) {
     // Yes. Bulk copy.
     move32(dstBytes + dstPos * width, srcBytes + srcPos * width, length * width);
-    UNIMPLEMENTED(WARNING) << "write barriers in System.arraycopy";
-    //dvmWriteBarrierArray(dstArray, dstPos, dstPos + length);
+    Heap::WriteBarrier(dstArray);
     return;
   }
 
@@ -228,8 +227,7 @@
   }
 
   move32(dstBytes + dstPos * width, srcBytes + srcPos * width, copyCount * width);
-  UNIMPLEMENTED(WARNING) << "write barriers in System.arraycopy";
-  //dvmWriteBarrierArray(dstArray, 0, copyCount);
+  Heap::WriteBarrier(dstArray);
   if (copyCount != length) {
     std::string actualSrcType(PrettyType(srcObj[copyCount]));
     std::string dstType(PrettyType(dstArray));
diff --git a/src/object.h b/src/object.h
index b9cab1d..3d11009 100644
--- a/src/object.h
+++ b/src/object.h
@@ -2269,7 +2269,7 @@
         dst_offset = MemberOffset(dst_offset.Uint32Value() + sizeof(Object*));
       }
     }
-    // TODO: bulk write barrier
+    Heap::WriteBarrier(dst);
   }
 }