diff --git a/R/master.r b/R/master.r
index 4b116fe..d3ada08 100644
--- a/R/master.r
+++ b/R/master.r
@@ -33,7 +33,7 @@ master = function(pool, iter, rettype="list", fail_on_error=TRUE,
     n_warnings = 0
     shutdown = FALSE
     kill_workers = FALSE
-    penv = pool$env()
+    penv = pool$env(work_chunk=work_chunk)
     obj_size = structure(sum(penv$size), class="object_size")
     obj_size_fmt = format(obj_size, big.mark=",", units="auto")
 
@@ -89,8 +89,8 @@ master = function(pool, iter, rettype="list", fail_on_error=TRUE,
         if (submit_index[1] <= n_calls) {
             # if we have work, send it to the worker
             submit_index = submit_index[submit_index <= n_calls]
-            pool$send(clustermq:::work_chunk(chunk, fun=fun, const=const,
-                rettype=rettype, common_seed=common_seed), chunk=chunk(iter, submit_index))
+            pool$send(work_chunk(chunk, fun=fun, const=const, rettype=rettype,
+                common_seed=common_seed), chunk=chunk(iter, submit_index))
             jobs_running = jobs_running + length(submit_index)
             submit_index = submit_index + chunk_size