diff --git a/ompi/mpi/c/gather.c.in b/ompi/mpi/c/gather.c.in
index 0cef27ae84f..e071da8d748 100644
--- a/ompi/mpi/c/gather.c.in
+++ b/ompi/mpi/c/gather.c.in
@@ -50,12 +50,13 @@ PROTOTYPE ERROR_CLASS gather(BUFFER sendbuf, COUNT sendcount, DATATYPE sendtype,
         ptrdiff_t ext;
 
         rank = ompi_comm_rank(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
             if(ompi_comm_rank(comm) == root) {
                 /* check whether root's send buffer is defined. */
+                memchecker_datatype(recvtype);
+                ompi_datatype_type_extent(recvtype, &ext);
                 if (MPI_IN_PLACE == sendbuf) {
                   memchecker_call(&opal_memchecker_base_isdefined,
                                   (char *)(recvbuf)+rank*ext,
diff --git a/ompi/mpi/c/gather_init.c.in b/ompi/mpi/c/gather_init.c.in
index 97ae216e7eb..6022a42bbf9 100644
--- a/ompi/mpi/c/gather_init.c.in
+++ b/ompi/mpi/c/gather_init.c.in
@@ -50,13 +50,14 @@ PROTOTYPE ERROR_CLASS gather_init(BUFFER sendbuf, COUNT sendcount, DATATYPE send
         ptrdiff_t ext;
 
         rank = ompi_comm_rank(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
             if(ompi_comm_rank(comm) == root) {
                 /* check whether root's send buffer is defined. */
                 if (MPI_IN_PLACE == sendbuf) {
+                  memchecker_datatype(recvtype);
+                  ompi_datatype_type_extent(recvtype, &ext);
                   memchecker_call(&opal_memchecker_base_isdefined,
                                   (char *)(recvbuf)+rank*ext,
                                   recvcount, recvtype);
diff --git a/ompi/mpi/c/gatherv.c.in b/ompi/mpi/c/gatherv.c.in
index 835243d3437..1d5dbe469ab 100644
--- a/ompi/mpi/c/gatherv.c.in
+++ b/ompi/mpi/c/gatherv.c.in
@@ -49,11 +49,12 @@ PROTOTYPE ERROR_CLASS gatherv(BUFFER sendbuf, COUNT sendcount, DATATYPE sendtype
         ptrdiff_t ext;
 
         size = ompi_comm_remote_size(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
             if(ompi_comm_rank(comm) == root) {
+                memchecker_datatype(recvtype);
+                ompi_datatype_type_extent(recvtype, &ext);
                 /* check whether root's send buffer is defined. */
                 if (MPI_IN_PLACE == sendbuf) {
                     for (i = 0; i < size; i++) {
@@ -66,7 +67,6 @@ PROTOTYPE ERROR_CLASS gatherv(BUFFER sendbuf, COUNT sendcount, DATATYPE sendtype
                     memchecker_call(&opal_memchecker_base_isdefined, sendbuf, sendcount, sendtype);
                 }
 
-                memchecker_datatype(recvtype);
                 /* check whether root's receive buffer is addressable. */
                 for (i = 0; i < size; i++) {
                     memchecker_call(&opal_memchecker_base_isaddressable,
@@ -82,6 +82,7 @@ PROTOTYPE ERROR_CLASS gatherv(BUFFER sendbuf, COUNT sendcount, DATATYPE sendtype
             if (MPI_ROOT == root) {
                 memchecker_datatype(recvtype);
                 /* check whether root's receive buffer is addressable. */
+                ompi_datatype_type_extent(recvtype, &ext);
                 for (i = 0; i < size; i++) {
                     memchecker_call(&opal_memchecker_base_isaddressable,
                                     (char *)(recvbuf)+displs[i]*ext,
diff --git a/ompi/mpi/c/igather.c.in b/ompi/mpi/c/igather.c.in
index b947a324081..1786e7056eb 100644
--- a/ompi/mpi/c/igather.c.in
+++ b/ompi/mpi/c/igather.c.in
@@ -51,13 +51,14 @@ PROTOTYPE ERROR_CLASS igather(BUFFER sendbuf, COUNT sendcount, DATATYPE sendtype
         ptrdiff_t ext;
 
         rank = ompi_comm_rank(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
             if(ompi_comm_rank(comm) == root) {
                 /* check whether root's send buffer is defined. */
                 if (MPI_IN_PLACE == sendbuf) {
+                  memchecker_datatype(recvtype);
+                  ompi_datatype_type_extent(recvtype, &ext);
                   memchecker_call(&opal_memchecker_base_isdefined,
                                   (char *)(recvbuf)+rank*ext,
                                   recvcount, recvtype);
diff --git a/ompi/mpi/c/iscatterv.c.in b/ompi/mpi/c/iscatterv.c.in
index 1791f64c5a2..0bd4bb96065 100644
--- a/ompi/mpi/c/iscatterv.c.in
+++ b/ompi/mpi/c/iscatterv.c.in
@@ -49,12 +49,12 @@ PROTOTYPE ERROR_CLASS iscatterv(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP_ARR
         ptrdiff_t ext;
 
         size = ompi_comm_remote_size(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
               if(ompi_comm_rank(comm) == root) {
                 memchecker_datatype(sendtype);
+                ompi_datatype_type_extent(sendtype, &ext);
                 /* check whether root's send buffer is defined. */
                 for (i = 0; i < size; i++) {
                     memchecker_call(&opal_memchecker_base_isdefined,
@@ -74,6 +74,7 @@ PROTOTYPE ERROR_CLASS iscatterv(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP_ARR
         } else {
             if(MPI_ROOT == root) {
                   memchecker_datatype(sendtype);
+                  ompi_datatype_type_extent(sendtype, &ext);
                   /* check whether root's send buffer is defined. */
                   for (i = 0; i < size; i++) {
                       memchecker_call(&opal_memchecker_base_isdefined,
diff --git a/ompi/mpi/c/scatterv.c.in b/ompi/mpi/c/scatterv.c.in
index 78eda87c80f..517f01bb503 100644
--- a/ompi/mpi/c/scatterv.c.in
+++ b/ompi/mpi/c/scatterv.c.in
@@ -49,12 +49,12 @@ PROTOTYPE ERROR_CLASS scatterv(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP_ARRA
         ptrdiff_t ext;
 
         size = ompi_comm_remote_size(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
               if(ompi_comm_rank(comm) == root) {
                 memchecker_datatype(sendtype);
+                ompi_datatype_type_extent(sendtype, &ext);
                 /* check whether root's send buffer is defined. */
                 for (i = 0; i < size; i++) {
                     memchecker_call(&opal_memchecker_base_isdefined,
@@ -74,6 +74,7 @@ PROTOTYPE ERROR_CLASS scatterv(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP_ARRA
         } else {
             if(MPI_ROOT == root) {
                   memchecker_datatype(sendtype);
+                  ompi_datatype_type_extent(sendtype, &ext);
                   /* check whether root's send buffer is defined. */
                   for (i = 0; i < size; i++) {
                       memchecker_call(&opal_memchecker_base_isdefined,
diff --git a/ompi/mpi/c/scatterv_init.c.in b/ompi/mpi/c/scatterv_init.c.in
index c42b0b1d9b5..18558e2b994 100644
--- a/ompi/mpi/c/scatterv_init.c.in
+++ b/ompi/mpi/c/scatterv_init.c.in
@@ -49,12 +49,12 @@ PROTOTYPE ERROR_CLASS scatterv_init(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP
         ptrdiff_t ext;
 
         size = ompi_comm_remote_size(comm);
-        ompi_datatype_type_extent(recvtype, &ext);
 
         memchecker_comm(comm);
         if(OMPI_COMM_IS_INTRA(comm)) {
               if(ompi_comm_rank(comm) == root) {
                 memchecker_datatype(sendtype);
+                ompi_datatype_type_extent(sendtype, &ext);
                 /* check whether root's send buffer is defined. */
                 for (i = 0; i < size; i++) {
                     memchecker_call(&opal_memchecker_base_isdefined,
@@ -74,6 +74,7 @@ PROTOTYPE ERROR_CLASS scatterv_init(BUFFER sendbuf, COUNT_ARRAY sendcounts, DISP
         } else {
             if(MPI_ROOT == root) {
                   memchecker_datatype(sendtype);
+                  ompi_datatype_type_extent(sendtype, &ext);
                   /* check whether root's send buffer is defined. */
                   for (i = 0; i < size; i++) {
                       memchecker_call(&opal_memchecker_base_isdefined,