diff --git a/vtkm/cont/AssignerMultiBlock.cxx b/vtkm/cont/AssignerMultiBlock.cxx
index 5406d4904..f4d83902c 100644
--- a/vtkm/cont/AssignerMultiBlock.cxx
+++ b/vtkm/cont/AssignerMultiBlock.cxx
@@ -38,12 +38,16 @@ namespace cont
 
 VTKM_CONT
 AssignerMultiBlock::AssignerMultiBlock(const vtkm::cont::MultiBlock& mb)
+  : AssignerMultiBlock(mb.GetNumberOfBlocks())
+{
+}
+
+VTKM_CONT
+AssignerMultiBlock::AssignerMultiBlock(vtkm::Id num_blocks)
   : diy::Assigner(vtkm::cont::EnvironmentTracker::GetCommunicator().size(), 1)
   , IScanBlockCounts()
 {
   auto comm = vtkm::cont::EnvironmentTracker::GetCommunicator();
-  const auto num_blocks = mb.GetNumberOfBlocks();
-
   if (comm.size() > 1)
   {
     vtkm::Id iscan;
diff --git a/vtkm/cont/AssignerMultiBlock.h b/vtkm/cont/AssignerMultiBlock.h
index 2d402cbb6..7bca18781 100644
--- a/vtkm/cont/AssignerMultiBlock.h
+++ b/vtkm/cont/AssignerMultiBlock.h
@@ -68,6 +68,9 @@ public:
   VTKM_CONT
   AssignerMultiBlock(const vtkm::cont::MultiBlock& mb);
 
+  VTKM_CONT
+  AssignerMultiBlock(vtkm::Id num_blocks);
+
   ///@{
   /// diy::Assigner API implementation.
   VTKM_CONT