diff --git a/src/mca/oob/tcp/oob_tcp.c b/src/mca/oob/tcp/oob_tcp.c
index 720c678a8c..6c4c0b0d00 100644
--- a/src/mca/oob/tcp/oob_tcp.c
+++ b/src/mca/oob/tcp/oob_tcp.c
@@ -49,6 +49,9 @@ int mca_oob_tcp_close(void)
     return OMPI_ERROR;
 }
 
+ompi_list_t mca_oob_tcp_peer_list;
+ompi_rb_tree_t mca_oob_tcp_peer_tree;
+
 /*
  * this function will temporarily return NULL so we don't use it
  */
diff --git a/src/mca/oob/tcp/oob_tcp.h b/src/mca/oob/tcp/oob_tcp.h
index fe1340a8c9..f278e95deb 100644
--- a/src/mca/oob/tcp/oob_tcp.h
+++ b/src/mca/oob/tcp/oob_tcp.h
@@ -18,11 +18,12 @@
 /*
  * the list of peers
  */
-ompi_list_t mca_oob_tcp_peer_list;
+extern ompi_list_t mca_oob_tcp_peer_list;
+
 /*
  * the tree of peers
  */
-ompi_rb_tree_t mca_oob_tcp_peer_tree;
+extern ompi_rb_tree_t mca_oob_tcp_peer_tree;
 
 
 #if defined(c_plusplus) || defined(__cplusplus)