diff --git a/src/allreduce_base.h b/src/allreduce_base.h
index 4194beb13..ef5567af1 100644
--- a/src/allreduce_base.h
+++ b/src/allreduce_base.h
@@ -90,7 +90,7 @@ class AllreduceBase : public IEngine {
                          PreprocFunction prepare_fun = NULL,
                          void *prepare_arg = NULL) {
     if (prepare_fun != NULL) prepare_fun(prepare_arg);
-    if (world_size == 1) return;
+    if (world_size == 1 || world_size == -1) return;
     utils::Assert(TryAllreduce(sendrecvbuf_,
                                type_nbytes, count, reducer) == kSuccess,
                   "Allreduce failed");
@@ -102,7 +102,7 @@ class AllreduceBase : public IEngine {
    * \param root the root worker id to broadcast the data
    */
   virtual void Broadcast(void *sendrecvbuf_, size_t total_size, int root) {
-    if (world_size == 1) return;
+    if (world_size == 1 || world_size == -1) return;
     utils::Assert(TryBroadcast(sendrecvbuf_, total_size, root) == kSuccess,
                   "Broadcast failed");
   }
diff --git a/src/allreduce_robust.cc b/src/allreduce_robust.cc
index c89b69542..fc47982f7 100644
--- a/src/allreduce_robust.cc
+++ b/src/allreduce_robust.cc
@@ -114,7 +114,7 @@ void AllreduceRobust::Allreduce(void *sendrecvbuf_,
  */
 void AllreduceRobust::Broadcast(void *sendrecvbuf_, size_t total_size, int root) {
   // skip action in single node
-  if (world_size == 1) return;
+  if (world_size == 1 || world_size == -1) return;
   bool recovered = RecoverExec(sendrecvbuf_, total_size, 0, seq_counter);
   // now we are free to remove the last result, if any
   if (resbuf.LastSeqNo() != -1 &&