diff --git a/ompi/mca/coll/libnbc/nbc_ialltoall.c b/ompi/mca/coll/libnbc/nbc_ialltoall.c
index 732a6064fe..c18096e050 100644
--- a/ompi/mca/coll/libnbc/nbc_ialltoall.c
+++ b/ompi/mca/coll/libnbc/nbc_ialltoall.c
@@ -51,8 +51,8 @@ int ompi_coll_libnbc_ialltoall(const void* sendbuf, int sendcount, MPI_Datatype
                                MPI_Datatype recvtype, struct ompi_communicator_t *comm, ompi_request_t ** request,
                                struct mca_coll_base_module_2_1_0_t *module)
 {
-  int rank, p, res, a2asize, datasize;
-  size_t sndsize;
+  int rank, p, res, datasize;
+  size_t a2asize, sndsize;
   NBC_Schedule *schedule;
   MPI_Aint rcvext, sndext;
 #ifdef NBC_CACHE_SCHEDULE
@@ -94,7 +94,7 @@ int ompi_coll_libnbc_ialltoall(const void* sendbuf, int sendcount, MPI_Datatype
      * total communicated size is smaller than 1<<17 *and* if we don't
      * have eager messages (msgsize < 1<<13) */
     alg = NBC_A2A_LINEAR;
-  } else if(a2asize < (1<<12)*p) {
+  } else if(a2asize < (1<<12)*(unsigned int)p) {
     /*alg = NBC_A2A_DISS;*/
     alg = NBC_A2A_LINEAR;
   } else
diff --git a/ompi/mca/coll/libnbc/nbc_ibcast.c b/ompi/mca/coll/libnbc/nbc_ibcast.c
index 83dd4ebad7..5f0470a133 100644
--- a/ompi/mca/coll/libnbc/nbc_ibcast.c
+++ b/ompi/mca/coll/libnbc/nbc_ibcast.c
@@ -1,11 +1,11 @@
 /* -*- Mode: C; c-basic-offset:2 ; indent-tabs-mode:nil -*- */
 /*
- * Copyright (c) 2006 The Trustees of Indiana University and Indiana
- *                    University Research and Technology
- *                    Corporation.  All rights reserved.
- * Copyright (c) 2006 The Technical University of Chemnitz. All
- *                    rights reserved.
- * Copyright (c) 2014      Research Organization for Information Science
+ * Copyright (c) 2006      The Trustees of Indiana University and Indiana
+ *                         University Research and Technology
+ *                         Corporation.  All rights reserved.
+ * Copyright (c) 2006      The Technical University of Chemnitz. All
+ *                         rights reserved.
+ * Copyright (c) 2014-2015 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2015      Los Alamos National Security, LLC. All rights
  *                         reserved.
@@ -20,7 +20,7 @@ static inline int bcast_sched_binomial(int rank, int p, int root, NBC_Schedule *
 static inline int bcast_sched_linear(int rank, int p, int root, NBC_Schedule *schedule, void *buffer, int count,
                                      MPI_Datatype datatype);
 static inline int bcast_sched_chain(int rank, int p, int root, NBC_Schedule *schedule, void *buffer, int count,
-                                    MPI_Datatype datatype, int fragsize, int size);
+                                    MPI_Datatype datatype, int fragsize, size_t size);
 
 #ifdef NBC_CACHE_SCHEDULE
 /* tree comparison function for schedule cache */
@@ -252,7 +252,7 @@ static inline int bcast_sched_linear(int rank, int p, int root, NBC_Schedule *sc
 }
 
 /* simple chained MPI_Ibcast */
-static inline int bcast_sched_chain(int rank, int p, int root, NBC_Schedule *schedule, void *buffer, int count, MPI_Datatype datatype, int fragsize, int size) {
+static inline int bcast_sched_chain(int rank, int p, int root, NBC_Schedule *schedule, void *buffer, int count, MPI_Datatype datatype, int fragsize, size_t size) {
   int res, vrank, rpeer, speer, numfrag, fragcount, thiscount;
   MPI_Aint ext;
   char *buf;
diff --git a/ompi/mca/coll/libnbc/nbc_ibcast_inter.c b/ompi/mca/coll/libnbc/nbc_ibcast_inter.c
index f9aa0d9a1b..8188ec6573 100644
--- a/ompi/mca/coll/libnbc/nbc_ibcast_inter.c
+++ b/ompi/mca/coll/libnbc/nbc_ibcast_inter.c
@@ -5,7 +5,7 @@
  *                         Corporation.  All rights reserved.
  * Copyright (c) 2006      The Technical University of Chemnitz. All
  *                         rights reserved.
- * Copyright (c) 2014      Research Organization for Information Science
+ * Copyright (c) 2014-2015 Research Organization for Information Science
  *                         and Technology (RIST). All rights reserved.
  * Copyright (c) 2015      Los Alamos National Security, LLC. All rights
  *                         reserved.
@@ -19,17 +19,10 @@ int ompi_coll_libnbc_ibcast_inter(void *buffer, int count, MPI_Datatype datatype
                                   struct ompi_communicator_t *comm, ompi_request_t ** request,
                                   struct mca_coll_base_module_2_1_0_t *module) {
   int res;
-  size_t size;
   NBC_Schedule *schedule;
   NBC_Handle *handle;
   ompi_coll_libnbc_module_t *libnbc_module = (ompi_coll_libnbc_module_t*) module;
 
-  res = ompi_datatype_type_size(datatype, &size);
-  if (MPI_SUCCESS != res) {
-    NBC_Error("MPI Error in ompi_datatype_type_size() (%i)", res);
-    return res;
-  }
-
   schedule = OBJ_NEW(NBC_Schedule);
   if (OPAL_UNLIKELY(NULL == schedule)) {
     return OMPI_ERR_OUT_OF_RESOURCE;
diff --git a/ompi/mca/coll/libnbc/nbc_ireduce.c b/ompi/mca/coll/libnbc/nbc_ireduce.c
index fbd15d942d..0045deb6a5 100644
--- a/ompi/mca/coll/libnbc/nbc_ireduce.c
+++ b/ompi/mca/coll/libnbc/nbc_ireduce.c
@@ -18,7 +18,7 @@
 static inline int red_sched_binomial (int rank, int p, int root, const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
                                       MPI_Op op, void *redbuf, NBC_Schedule *schedule, NBC_Handle *handle);
 static inline int red_sched_chain (int rank, int p, int root, const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
-                                   MPI_Op op, int ext, int size, NBC_Schedule *schedule, NBC_Handle *handle, int fragsize);
+                                   MPI_Op op, int ext, size_t size, NBC_Schedule *schedule, NBC_Handle *handle, int fragsize);
 
 static inline int red_sched_linear (int rank, int rsize, int root, const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
                                     MPI_Op op, NBC_Schedule *schedule, NBC_Handle *handle);
@@ -360,7 +360,7 @@ static inline int red_sched_binomial (int rank, int p, int root, const void *sen
 
 /* chain send ... */
 static inline int red_sched_chain (int rank, int p, int root, const void *sendbuf, void *recvbuf, int count, MPI_Datatype datatype,
-                                   MPI_Op op, int ext, int size, NBC_Schedule *schedule, NBC_Handle *handle, int fragsize) {
+                                   MPI_Op op, int ext, size_t size, NBC_Schedule *schedule, NBC_Handle *handle, int fragsize) {
   int res, vrank, rpeer, speer, numfrag, fragcount, thiscount;
   long offset;