diff --git a/ompi/mpi/c/pack.c b/ompi/mpi/c/pack.c
index ab00e08688..d841e058ca 100644
--- a/ompi/mpi/c/pack.c
+++ b/ompi/mpi/c/pack.c
@@ -73,7 +73,7 @@ int MPI_Pack(void *inbuf, int incount, MPI_Datatype datatype,
 
     /* Prepare the iovec with all informations */
     invec.iov_base = (char*) outbuf + (*position);
-    invec.iov_len = outsize - (*position);
+    invec.iov_len = size;
 
     /* Do the actual packing */
     iov_count = 1;
diff --git a/ompi/mpi/c/pack_external.c b/ompi/mpi/c/pack_external.c
index 7d99290a1d..1af7412d4f 100644
--- a/ompi/mpi/c/pack_external.c
+++ b/ompi/mpi/c/pack_external.c
@@ -71,7 +71,7 @@ int MPI_Pack_external(char *datarep, void *inbuf, int incount,
 
     /* Prepare the iovec with all informations */
     invec.iov_base = (char*) outbuf + (*position);
-    invec.iov_len = outsize - (*position);
+    invec.iov_len = size;
 
     /* Do the actual packing */
     iov_count = 1;
diff --git a/ompi/mpi/c/unpack.c b/ompi/mpi/c/unpack.c
index 63115ab907..4e8b93879c 100644
--- a/ompi/mpi/c/unpack.c
+++ b/ompi/mpi/c/unpack.c
@@ -77,7 +77,7 @@ int MPI_Unpack(void *inbuf, int insize, int *position,
         
         /* Prepare the iovec with all informations */
         outvec.iov_base = (char*) inbuf + (*position);
-        outvec.iov_len = insize - (*position);
+        outvec.iov_len = size;
         
         /* Do the actual unpacking */
         iov_count = 1;
diff --git a/ompi/mpi/c/unpack_external.c b/ompi/mpi/c/unpack_external.c
index 41d56729b3..2a1679aa84 100644
--- a/ompi/mpi/c/unpack_external.c
+++ b/ompi/mpi/c/unpack_external.c
@@ -68,7 +68,7 @@ int MPI_Unpack_external (char *datarep, void *inbuf, MPI_Aint insize,
 
     /* Prepare the iovec with all informations */
     outvec.iov_base = (char*) inbuf + (*position);
-    outvec.iov_len = insize - (*position);
+    outvec.iov_len = size;
 
     /* Do the actual unpacking */
     iov_count = 1;