diff --git a/src/mpi.f90 b/src/mpi.f90
index 7df44db..8d15df9 100644
--- a/src/mpi.f90
+++ b/src/mpi.f90
@@ -1,10 +1,11 @@
 module mpi
     implicit none
     integer, parameter :: MPI_THREAD_FUNNELED = 1
-    ! not sure if this is correct really
-    integer, parameter :: MPI_INTEGER = 2
-    integer, parameter :: MPI_REAL4 = 0
-    integer, parameter :: MPI_REAL8 = 1
+
+    integer, parameter :: MPI_INTEGER = -10002
+    integer, parameter :: MPI_REAL4 = -10013
+    integer, parameter :: MPI_REAL8 = -10014
+
     integer, parameter :: MPI_COMM_TYPE_SHARED = 1
     integer, parameter :: MPI_PROC_NULL = -1
     integer, parameter :: MPI_SUCCESS = 0
diff --git a/src/mpi_wrapper.c b/src/mpi_wrapper.c
index 15084eb..98a9d2a 100644
--- a/src/mpi_wrapper.c
+++ b/src/mpi_wrapper.c
@@ -3,11 +3,34 @@
 #include <stdio.h>
 
 #define MPI_STATUS_SIZE 5
+
 #define FORTRAN_MPI_COMM_WORLD -1000
 #define FORTRAN_MPI_INFO_NULL -2000
 #define FORTRAN_MPI_IN_PLACE -1002
+
 #define FORTRAN_MPI_SUM -2300
 
+#define FORTRAN_MPI_INTEGER -10002
+#define FORTRAN_MPI_REAL4 -10013
+#define FORTRAN_MPI_REAL8 -10014
+
+
+MPI_Datatype get_c_datatype_from_fortran(int datatype) {
+    MPI_Datatype c_datatype;
+    switch (datatype) {
+        case FORTRAN_MPI_REAL4:
+            c_datatype = MPI_FLOAT;
+            break;
+        case FORTRAN_MPI_REAL8:
+            c_datatype = MPI_DOUBLE;
+            break;
+        case FORTRAN_MPI_INTEGER:
+            c_datatype = MPI_INT;
+            break;
+    }
+    return c_datatype;
+}
+
 MPI_Info get_c_info_from_fortran(int info) {
     if (info == FORTRAN_MPI_INFO_NULL) {
         return MPI_INFO_NULL;
@@ -34,38 +57,13 @@ MPI_Comm get_c_comm_from_fortran(int comm_f) {
 
 void mpi_bcast_int_wrapper(int *buffer, int *count, int *datatype_f, int *root, int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 2:
-            datatype = MPI_INT;
-            break;
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
     *ierror = MPI_Bcast(buffer, *count, datatype, *root, comm);
 }
 
 void mpi_bcast_real_wrapper(double *buffer, int *count, int *datatype_f, int *root, int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
     *ierror = MPI_Bcast(buffer, *count, datatype, *root, comm);
 }
 
@@ -74,24 +72,8 @@ void mpi_allgather_int_wrapper(const int *sendbuf, int *sendcount, int *sendtype
                                int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
 
-    MPI_Datatype sendtype, recvtype;
-    switch (*sendtype_f) {
-        case 2:
-            sendtype = MPI_INT;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
-
-    switch (*recvtype_f) {
-        case 2:
-            recvtype = MPI_INT;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype sendtype = get_c_datatype_from_fortran(*sendtype_f);
+    MPI_Datatype recvtype = get_c_datatype_from_fortran(*recvtype_f);
 
     *ierror = MPI_Allgather(sendbuf, *sendcount, sendtype,
                             recvbuf, *recvcount, recvtype, comm);
@@ -102,30 +84,8 @@ void mpi_allgather_real_wrapper(const double *sendbuf, int *sendcount, int *send
                                int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
 
-    MPI_Datatype sendtype, recvtype;
-    switch (*sendtype_f) {
-        case 0:
-            sendtype = MPI_FLOAT;
-            break;
-        case 1:
-            sendtype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
-
-    switch (*recvtype_f) {
-        case 0:
-            recvtype = MPI_FLOAT;
-            break;
-        case 1:
-            recvtype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype sendtype = get_c_datatype_from_fortran(*sendtype_f);
+    MPI_Datatype recvtype = get_c_datatype_from_fortran(*recvtype_f);
 
     *ierror = MPI_Allgather(sendbuf, *sendcount, sendtype,
                             recvbuf, *recvcount, recvtype, comm);
@@ -135,18 +95,7 @@ void mpi_isend_wrapper(const double *buf, int *count, int *datatype_f,
                         int *dest, int *tag, int *comm_f, int *request_f,
                         int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *request_f = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
 
     MPI_Request request;
     *ierror = MPI_Isend(buf, *count, datatype, *dest, *tag, comm, &request);
@@ -157,18 +106,7 @@ void mpi_irecv_wrapper(double *buf, int *count, int *datatype_f,
                         int *source, int *tag, int *comm_f, int *request_f,
                         int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *request_f = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
 
     MPI_Request request;
     *ierror = MPI_Irecv(buf, *count, datatype, *source, *tag, comm, &request);
@@ -178,18 +116,7 @@ void mpi_irecv_wrapper(double *buf, int *count, int *datatype_f,
 void mpi_allreduce_wrapper_real(const double *sendbuf, double *recvbuf, int *count,
                             int *datatype_f, int *op_f, int *comm_f, int *ierror) {
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
 
     // I'm a little doubtful: as how would it identify that this part
     // is supposed to be for MPI_SUM?
@@ -244,18 +171,7 @@ void mpi_comm_split_type_wrapper(int *comm_f, int *split_type, int *key,
 
 void mpi_recv_wrapper(double *buf, int *count, int *datatype_f, int *source,
                     int *tag, int *comm_f, int *status_f, int *ierror) {
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
 
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
     MPI_Status status;
@@ -294,18 +210,7 @@ void mpi_waitall_wrapper(int *count, int *array_of_requests_f,
 
 void mpi_ssend_wrapper(double *buf, int *count, int *datatype_f, int *dest,
                        int *tag, int *comm_f, int *ierror) {
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_comm_from_fortran(*datatype_f);
 
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
     *ierror = MPI_Ssend(buf, *count, datatype, *dest, *tag, comm);
@@ -345,21 +250,8 @@ void mpi_cart_sub_wrapper(int *  comm_f, int * rmains_dims, int * newcomm_f, int
 void mpi_reduce_wrapper(const int* sendbuf, int* recvbuf, int* count, int* datatype_f,
                         int* op_f, int* root, int* comm_f, int* ierror)
 {
-    MPI_Datatype datatype;
-    switch (*datatype_f) {
-        case 2:
-            datatype = MPI_INT;
-            break;
-        case 0:
-            datatype = MPI_FLOAT;
-            break;
-        case 1:
-            datatype = MPI_DOUBLE;
-            break;
-        default:
-            *ierror = -1;
-            return;
-    }
+    MPI_Datatype datatype = get_c_datatype_from_fortran(*datatype_f);
+
     MPI_Op op = get_c_op_from_fortran(*op_f);
     MPI_Comm comm = get_c_comm_from_fortran(*comm_f);
     *ierror = MPI_Reduce(sendbuf, recvbuf, *count, datatype, op, *root, comm);