diff --git a/src/aiori-DUMMY.c b/src/aiori-DUMMY.c
index ce8933c..2e4feb5 100755
--- a/src/aiori-DUMMY.c
+++ b/src/aiori-DUMMY.c
@@ -48,7 +48,7 @@ static option_help * DUMMY_options(aiori_mod_opt_t ** init_backend_options, aior
 
 static int count_init = 0;
 
-static void *DUMMY_Create(char *testFileName, int iorflags, aiori_mod_opt_t * options)
+static aiori_fd_t *DUMMY_Create(char *testFileName, int iorflags, aiori_mod_opt_t * options)
 {
   if(count_init <= 0){
     ERR("DUMMY missing initialization in create\n");
@@ -63,10 +63,10 @@ static void *DUMMY_Create(char *testFileName, int iorflags, aiori_mod_opt_t * op
       nanosleep( & wait, NULL);
     }
   }
-  return current++;
+  return (aiori_fd_t*) current++;
 }
 
-static void *DUMMY_Open(char *testFileName, int flags, aiori_mod_opt_t * options)
+static aiori_fd_t *DUMMY_Open(char *testFileName, int flags, aiori_mod_opt_t * options)
 {
   if(count_init <= 0){
     ERR("DUMMY missing initialization in open\n");
@@ -74,10 +74,10 @@ static void *DUMMY_Open(char *testFileName, int flags, aiori_mod_opt_t * options
   if(verbose > 4){
     fprintf(out_logfile, "DUMMY open: %s = %p\n", testFileName, current);
   }
-  return current++;
+  return (aiori_fd_t*) current++;
 }
 
-static void DUMMY_Fsync(void *fd, aiori_mod_opt_t * options)
+static void DUMMY_Fsync(aiori_fd_t *fd, aiori_mod_opt_t * options)
 {
   if(verbose > 4){
     fprintf(out_logfile, "DUMMY fsync %p\n", fd);
@@ -89,7 +89,7 @@ static void DUMMY_Sync(aiori_mod_opt_t * options)
 {
 }
 
-static void DUMMY_Close(void *fd, aiori_mod_opt_t * options)
+static void DUMMY_Close(aiori_fd_t *fd, aiori_mod_opt_t * options)
 {
   if(verbose > 4){
     fprintf(out_logfile, "DUMMY close %p\n", fd);
@@ -116,7 +116,7 @@ static IOR_offset_t DUMMY_GetFileSize(aiori_mod_opt_t * options, MPI_Comm testCo
   return 0;
 }
 
-static IOR_offset_t DUMMY_Xfer(int access, void *file, IOR_size_t * buffer, IOR_offset_t length, aiori_mod_opt_t * options){
+static IOR_offset_t DUMMY_Xfer(int access, aiori_fd_t *file, IOR_size_t * buffer, IOR_offset_t length, aiori_mod_opt_t * options){
   if(verbose > 4){
     fprintf(out_logfile, "DUMMY xfer: %p\n", file);
   }
diff --git a/src/aiori-HDF5.c b/src/aiori-HDF5.c
index 203aa3f..6669902 100755
--- a/src/aiori-HDF5.c
+++ b/src/aiori-HDF5.c
@@ -83,14 +83,14 @@
 
 static IOR_offset_t SeekOffset(void *, IOR_offset_t, aiori_mod_opt_t *);
 static void SetupDataSet(void *, aiori_mod_opt_t *);
-static void *HDF5_Create(char *, int flags, aiori_mod_opt_t *);
-static void *HDF5_Open(char *, int flags, aiori_mod_opt_t *);
-static IOR_offset_t HDF5_Xfer(int, void *, IOR_size_t *,
+static aiori_fd_t *HDF5_Create(char *, int flags, aiori_mod_opt_t *);
+static aiori_fd_t *HDF5_Open(char *, int flags, aiori_mod_opt_t *);
+static IOR_offset_t HDF5_Xfer(int, aiori_fd_t *, IOR_size_t *,
                            IOR_offset_t, aiori_mod_opt_t *);
-static void HDF5_Close(void *, aiori_mod_opt_t *);
+static void HDF5_Close(aiori_fd_t *, aiori_mod_opt_t *);
 static void HDF5_Delete(char *, aiori_mod_opt_t *);
 static char* HDF5_GetVersion();
-static void HDF5_Fsync(void *, aiori_mod_opt_t *);
+static void HDF5_Fsync(aiori_fd_t *, aiori_mod_opt_t *);
 static IOR_offset_t HDF5_GetFileSize(aiori_mod_opt_t *, MPI_Comm, char *);
 static int HDF5_Access(const char *, int, aiori_mod_opt_t *);
 static void HDF5_init_xfer_options(IOR_param_t * params);
@@ -197,7 +197,7 @@ static int HDF5_check_params(aiori_mod_opt_t * options){
 /*
  * Create and open a file through the HDF5 interface.
  */
-static void *HDF5_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
+static aiori_fd_t *HDF5_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         return HDF5_Open(testFileName, flags, param);
 }
@@ -205,7 +205,7 @@ static void *HDF5_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
 /*
  * Open a file through the HDF5 interface.
  */
-static void *HDF5_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
+static aiori_fd_t *HDF5_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         HDF5_options_t *o = (HDF5_options_t*) param;
         hid_t accessPropList, createPropList;
@@ -410,13 +410,13 @@ static void *HDF5_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
         if (mpiHints != MPI_INFO_NULL)
                 MPI_Info_free(&mpiHints);
 
-        return (fd);
+        return (aiori_fd_t*)(fd);
 }
 
 /*
  * Write or read access to file using the HDF5 interface.
  */
-static IOR_offset_t HDF5_Xfer(int access, void *fd, IOR_size_t * buffer,
+static IOR_offset_t HDF5_Xfer(int access, aiori_fd_t *fd, IOR_size_t * buffer,
                               IOR_offset_t length, aiori_mod_opt_t * param)
 {
         static int firstReadCheck = FALSE, startNewDataSet;
@@ -495,15 +495,14 @@ static IOR_offset_t HDF5_Xfer(int access, void *fd, IOR_size_t * buffer,
 /*
  * Perform fsync().
  */
-static void HDF5_Fsync(void *fd, aiori_mod_opt_t * param)
+static void HDF5_Fsync(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
-        ;
 }
 
 /*
  * Close a file through the HDF5 interface.
  */
-static void HDF5_Close(void *fd, aiori_mod_opt_t * param)
+static void HDF5_Close(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
         if(ior_param->dryRun)
           return;
diff --git a/src/aiori-MMAP.c b/src/aiori-MMAP.c
index 5a920a7..3b8c203 100644
--- a/src/aiori-MMAP.c
+++ b/src/aiori-MMAP.c
@@ -26,12 +26,12 @@
 #include "utilities.h"
 
 /**************************** P R O T O T Y P E S *****************************/
-static void *MMAP_Create(char *, int flags, aiori_mod_opt_t *);
-static void *MMAP_Open(char *, int flags, aiori_mod_opt_t *);
-static IOR_offset_t MMAP_Xfer(int, void *, IOR_size_t *,
+static aiori_fd_t *MMAP_Create(char *, int flags, aiori_mod_opt_t *);
+static aiori_fd_t *MMAP_Open(char *, int flags, aiori_mod_opt_t *);
+static IOR_offset_t MMAP_Xfer(int, aiori_fd_t *, IOR_size_t *,
                                IOR_offset_t, aiori_mod_opt_t *);
-static void MMAP_Close(void *, aiori_mod_opt_t *);
-static void MMAP_Fsync(void *, aiori_mod_opt_t *);
+static void MMAP_Close(aiori_fd_t *, aiori_mod_opt_t *);
+static void MMAP_Fsync(aiori_fd_t *, aiori_mod_opt_t *);
 static option_help * MMAP_options(aiori_mod_opt_t ** init_backend_options, aiori_mod_opt_t * init_values);
 static void MMAP_init_xfer_options(IOR_param_t * params);
 static int MMAP_check_params(aiori_mod_opt_t * options);
@@ -130,32 +130,32 @@ static void ior_mmap_file(int *file, int mflags, void *param)
 /*
  * Creat and open a file through the POSIX interface, then setup mmap.
  */
-static void *MMAP_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
+static aiori_fd_t *MMAP_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         int *fd;
 
-        fd = POSIX_Create(testFileName, flags, param);
+        fd = (int*) POSIX_Create(testFileName, flags, param);
         if (ftruncate(*fd, ior_param->expectedAggFileSize) != 0)
                 ERR("ftruncate() failed");
         ior_mmap_file(fd, flags, param);
-        return ((void *)fd);
+        return ((aiori_fd_t *)fd);
 }
 
 /*
  * Open a file through the POSIX interface and setup mmap.
  */
-static void *MMAP_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
+static aiori_fd_t *MMAP_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         int *fd;
-        fd = POSIX_Open(testFileName, flags, param);
+        fd = (int*) POSIX_Open(testFileName, flags, param);
         ior_mmap_file(fd, flags, param);
-        return ((void *)fd);
+        return ((aiori_fd_t *)fd);
 }
 
 /*
  * Write or read access to file using mmap
  */
-static IOR_offset_t MMAP_Xfer(int access, void *file, IOR_size_t * buffer,
+static IOR_offset_t MMAP_Xfer(int access, aiori_fd_t *file, IOR_size_t * buffer,
                                IOR_offset_t length, aiori_mod_opt_t * param)
 {
         mmap_options_t *o = (mmap_options_t*) param;
@@ -178,7 +178,7 @@ static IOR_offset_t MMAP_Xfer(int access, void *file, IOR_size_t * buffer,
 /*
  * Perform msync().
  */
-static void MMAP_Fsync(void *fd, aiori_mod_opt_t * param)
+static void MMAP_Fsync(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
         mmap_options_t *o = (mmap_options_t*) param;
         if (msync(o->mmap_ptr, ior_param->expectedAggFileSize, MS_SYNC) != 0)
@@ -188,7 +188,7 @@ static void MMAP_Fsync(void *fd, aiori_mod_opt_t * param)
 /*
  * Close a file through the POSIX interface, after tear down the mmap.
  */
-static void MMAP_Close(void *fd, aiori_mod_opt_t * param)
+static void MMAP_Close(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
         mmap_options_t *o = (mmap_options_t*) param;
         if (munmap(o->mmap_ptr, ior_param->expectedAggFileSize) != 0)
diff --git a/src/aiori-MPIIO.c b/src/aiori-MPIIO.c
index f366872..81ec0be 100755
--- a/src/aiori-MPIIO.c
+++ b/src/aiori-MPIIO.c
@@ -33,13 +33,13 @@
 
 static IOR_offset_t SeekOffset(MPI_File, IOR_offset_t, aiori_mod_opt_t *);
 
-static void *MPIIO_Create(char *, int iorflags, aiori_mod_opt_t *);
-static void *MPIIO_Open(char *, int flags, aiori_mod_opt_t *);
-static IOR_offset_t MPIIO_Xfer(int, void *, IOR_size_t *,
+static aiori_fd_t *MPIIO_Create(char *, int iorflags, aiori_mod_opt_t *);
+static aiori_fd_t *MPIIO_Open(char *, int flags, aiori_mod_opt_t *);
+static IOR_offset_t MPIIO_Xfer(int, aiori_fd_t *, IOR_size_t *,
                                    IOR_offset_t, aiori_mod_opt_t *);
-static void MPIIO_Close(void *, aiori_mod_opt_t *);
+static void MPIIO_Close(aiori_fd_t *, aiori_mod_opt_t *);
 static char* MPIIO_GetVersion();
-static void MPIIO_Fsync(void *, aiori_mod_opt_t *);
+static void MPIIO_Fsync(aiori_fd_t *, aiori_mod_opt_t *);
 static void MPIIO_init_xfer_options(IOR_param_t * params);
 static int MPIIO_check_params(aiori_mod_opt_t * options);
 
@@ -172,7 +172,7 @@ int MPIIO_Access(const char *path, int mode, aiori_mod_opt_t *module_options)
 /*
  * Create and open a file through the MPIIO interface.
  */
-static void *MPIIO_Create(char *testFileName, int iorflags, aiori_mod_opt_t * module_options)
+static aiori_fd_t *MPIIO_Create(char *testFileName, int iorflags, aiori_mod_opt_t * module_options)
 {
   return MPIIO_Open(testFileName, iorflags, module_options);
 }
@@ -180,7 +180,7 @@ static void *MPIIO_Create(char *testFileName, int iorflags, aiori_mod_opt_t * mo
 /*
  * Open a file through the MPIIO interface.  Setup file view.
  */
-static void *MPIIO_Open(char *testFileName, int flags, aiori_mod_opt_t * module_options)
+static aiori_fd_t *MPIIO_Open(char *testFileName, int flags, aiori_mod_opt_t * module_options)
 {
         mpiio_options_t * param = (mpiio_options_t*) module_options;
         int fd_mode = (int)0,
@@ -328,7 +328,7 @@ static void *MPIIO_Open(char *testFileName, int flags, aiori_mod_opt_t * module_
 /*
  * Write or read access to file using the MPIIO interface.
  */
-static IOR_offset_t MPIIO_Xfer(int access, void * fdp, IOR_size_t * buffer,
+static IOR_offset_t MPIIO_Xfer(int access, aiori_fd_t * fdp, IOR_size_t * buffer,
                                IOR_offset_t length, aiori_mod_opt_t * module_options)
 {
         /* NOTE: The second arg is (void *) for reads, and (const void *)
@@ -464,7 +464,7 @@ static IOR_offset_t MPIIO_Xfer(int access, void * fdp, IOR_size_t * buffer,
 /*
  * Perform fsync().
  */
-static void MPIIO_Fsync(void *fdp, aiori_mod_opt_t * module_options)
+static void MPIIO_Fsync(aiori_fd_t *fdp, aiori_mod_opt_t * module_options)
 {
   mpiio_options_t * param = (mpiio_options_t*) module_options;
   if(param->dry_run)
@@ -477,7 +477,7 @@ static void MPIIO_Fsync(void *fdp, aiori_mod_opt_t * module_options)
 /*
  * Close a file through the MPIIO interface.
  */
-static void MPIIO_Close(void *fdp, aiori_mod_opt_t * module_options)
+static void MPIIO_Close(aiori_fd_t *fdp, aiori_mod_opt_t * module_options)
 {
         mpiio_options_t * param = (mpiio_options_t*) module_options;
         mpiio_fd_t * mfd = (mpiio_fd_t*) fdp;
diff --git a/src/aiori-POSIX.c b/src/aiori-POSIX.c
index 4ecc557..43c5261 100755
--- a/src/aiori-POSIX.c
+++ b/src/aiori-POSIX.c
@@ -68,9 +68,9 @@
 #endif
 
 /**************************** P R O T O T Y P E S *****************************/
-static IOR_offset_t POSIX_Xfer(int, void *, IOR_size_t *,
+static IOR_offset_t POSIX_Xfer(int, aiori_fd_t *, IOR_size_t *,
                                IOR_offset_t, aiori_mod_opt_t *);
-static void POSIX_Fsync(void *, aiori_mod_opt_t *);
+static void POSIX_Fsync(aiori_fd_t *, aiori_mod_opt_t *);
 static void POSIX_Sync(aiori_mod_opt_t * );
 static int POSIX_check_params(aiori_mod_opt_t * options);
 
@@ -372,7 +372,7 @@ bool beegfs_createFilePath(char* filepath, mode_t mode, int numTargets, int chun
 /*
  * Creat and open a file through the POSIX interface.
  */
-void *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
+aiori_fd_t *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         int fd_oflag = O_BINARY;
         int mode = 0664;
@@ -387,7 +387,7 @@ void *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
         }
 
         if(ior_param->dryRun)
-          return 0;
+          return (aiori_fd_t*) 0;
 
 #ifdef HAVE_LUSTRE_LUSTRE_USER_H
 /* Add a #define for FASYNC if not available, as it forms part of
@@ -483,7 +483,7 @@ void *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * param)
                 gpfs_free_all_locks(*fd);
         }
 #endif
-        return ((void *)fd);
+        return (aiori_fd_t*) fd;
 }
 
 /*
@@ -503,7 +503,7 @@ int POSIX_Mknod(char *testFileName)
 /*
  * Open a file through the POSIX interface.
  */
-void *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
+aiori_fd_t *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
 {
         int fd_oflag = O_BINARY;
         int *fd;
@@ -519,7 +519,7 @@ void *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
         fd_oflag |= O_RDWR;
 
         if(ior_param->dryRun)
-          return 0;
+          return (aiori_fd_t*) 0;
 
         *fd = open64(testFileName, fd_oflag);
         if (*fd < 0)
@@ -542,13 +542,13 @@ void *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * param)
                 gpfs_free_all_locks(*fd);
         }
 #endif
-        return ((void *)fd);
+        return (aiori_fd_t*) fd;
 }
 
 /*
  * Write or read access to file using the POSIX interface.
  */
-static IOR_offset_t POSIX_Xfer(int access, void *file, IOR_size_t * buffer,
+static IOR_offset_t POSIX_Xfer(int access, aiori_fd_t *file, IOR_size_t * buffer,
                                IOR_offset_t length, aiori_mod_opt_t * param)
 {
         int xferRetries = 0;
@@ -587,8 +587,9 @@ static IOR_offset_t POSIX_Xfer(int access, void *file, IOR_size_t * buffer,
                         if (rc == -1)
                                 ERRF("write(%d, %p, %lld) failed",
                                         fd, (void*)ptr, remaining);
-                        if (ior_param->fsyncPerWrite == TRUE)
-                                POSIX_Fsync(&fd, param);
+                        if (ior_param->fsyncPerWrite == TRUE){
+                          POSIX_Fsync((aiori_fd_t*) &fd, param);
+                        }
                 } else {        /* READ or CHECK */
                         if (verbose >= VERBOSE_4) {
                                 fprintf(stdout,
@@ -634,7 +635,7 @@ static IOR_offset_t POSIX_Xfer(int access, void *file, IOR_size_t * buffer,
 /*
  * Perform fsync().
  */
-static void POSIX_Fsync(void *fd, aiori_mod_opt_t * param)
+static void POSIX_Fsync(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
         if (fsync(*(int *)fd) != 0)
                 EWARNF("fsync(%d) failed", *(int *)fd);
@@ -653,7 +654,7 @@ static void POSIX_Sync(aiori_mod_opt_t * param)
 /*
  * Close a file through the POSIX interface.
  */
-void POSIX_Close(void *fd, aiori_mod_opt_t * param)
+void POSIX_Close(aiori_fd_t *fd, aiori_mod_opt_t * param)
 {
         if(ior_param->dryRun)
           return;
diff --git a/src/aiori.h b/src/aiori.h
index 7662e8f..76d9f6a 100755
--- a/src/aiori.h
+++ b/src/aiori.h
@@ -72,22 +72,26 @@ typedef struct aiori_mod_opt_t{
   void * dummy;
 } aiori_mod_opt_t;
 
+typedef struct aiori_fd_t{
+  void * dummy;
+} aiori_fd_t;
+
 typedef struct ior_aiori {
         char *name;
         char *name_legacy;
-        void *(*create)(char *, int iorflags, aiori_mod_opt_t *);
+        aiori_fd_t *(*create)(char *, int iorflags, aiori_mod_opt_t *);
         int (*mknod)(char *);
-        void *(*open)(char *, int iorflags, aiori_mod_opt_t *);
+        aiori_fd_t *(*open)(char *, int iorflags, aiori_mod_opt_t *);
         /*
          Allow to set generic transfer options that shall be applied to any subsequent IO call.
         */
         void (*init_xfer_options)(IOR_param_t * params);
-        IOR_offset_t (*xfer)(int, void *, IOR_size_t *,
+        IOR_offset_t (*xfer)(int, aiori_fd_t *, IOR_size_t *,
                              IOR_offset_t, aiori_mod_opt_t *);
-        void (*close)(void *, aiori_mod_opt_t *);
+        void (*close)(aiori_fd_t *, aiori_mod_opt_t *);
         void (*delete)(char *, aiori_mod_opt_t *);
         char* (*get_version)(void);
-        void (*fsync)(void *, aiori_mod_opt_t *);
+        void (*fsync)(aiori_fd_t *, aiori_mod_opt_t *);
         IOR_offset_t (*get_file_size)(aiori_mod_opt_t * module_options, MPI_Comm, char *);
         int (*statfs) (const char *, ior_aiori_statfs_t *, aiori_mod_opt_t * module_options);
         int (*mkdir) (const char *path, mode_t mode, aiori_mod_opt_t * module_options);
@@ -142,12 +146,12 @@ int aiori_posix_access (const char *path, int mode, aiori_mod_opt_t * module_opt
 int aiori_posix_stat (const char *path, struct stat *buf, aiori_mod_opt_t * module_options);
 void aiori_posix_init_xfer_options(IOR_param_t * params);
 
-void *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * module_options);
+aiori_fd_t *POSIX_Create(char *testFileName, int flags, aiori_mod_opt_t * module_options);
 int POSIX_Mknod(char *testFileName);
-void *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * module_options);
+aiori_fd_t *POSIX_Open(char *testFileName, int flags, aiori_mod_opt_t * module_options);
 IOR_offset_t POSIX_GetFileSize(aiori_mod_opt_t * test, MPI_Comm testComm, char *testFileName);
 void POSIX_Delete(char *testFileName, aiori_mod_opt_t * module_options);
-void POSIX_Close(void *fd, aiori_mod_opt_t * module_options);
+void POSIX_Close(aiori_fd_t *fd, aiori_mod_opt_t * module_options);
 option_help * POSIX_options(aiori_mod_opt_t ** init_backend_options, aiori_mod_opt_t * init_values);
 
 
diff --git a/src/ior.c b/src/ior.c
index 3323b7f..7dbf80b 100755
--- a/src/ior.c
+++ b/src/ior.c
@@ -55,7 +55,7 @@ static void InitTests(IOR_test_t * , MPI_Comm);
 static void TestIoSys(IOR_test_t *);
 static void ValidateTests(IOR_param_t *);
 static IOR_offset_t WriteOrRead(IOR_param_t *test, IOR_results_t *results,
-                                void *fd, const int access,
+                                aiori_fd_t *fd, const int access,
                                 IOR_io_buffers *ioBuffers);
 
 static void test_initialize(IOR_test_t * test){
@@ -1231,7 +1231,7 @@ static void TestIoSys(IOR_test_t *test)
         double startTime;
         int pretendRank;
         int rep;
-        void *fd;
+        aiori_fd_t *fd;
         MPI_Group orig_group, new_group;
         int range[3];
         IOR_offset_t dataMoved; /* for data rate calculation */
@@ -1781,7 +1781,7 @@ IOR_offset_t *GetOffsetArrayRandom(IOR_param_t * test, int pretendRank, int acce
 }
 
 static IOR_offset_t WriteOrReadSingle(IOR_offset_t pairCnt, IOR_offset_t *offsetArray, int pretendRank,
-  IOR_offset_t * transferCount, int * errors, IOR_param_t * test, int * fd, IOR_io_buffers* ioBuffers, int access){
+  IOR_offset_t * transferCount, int * errors, IOR_param_t * test, aiori_fd_t * fd, IOR_io_buffers* ioBuffers, int access){
   IOR_offset_t amtXferred = 0;
   IOR_offset_t transfer;
 
@@ -1850,7 +1850,7 @@ static IOR_offset_t WriteOrReadSingle(IOR_offset_t pairCnt, IOR_offset_t *offset
  * out the data to each block in transfer sizes, until the remainder left is 0.
  */
 static IOR_offset_t WriteOrRead(IOR_param_t *test, IOR_results_t *results,
-                                void *fd, const int access, IOR_io_buffers *ioBuffers)
+                                aiori_fd_t *fd, const int access, IOR_io_buffers *ioBuffers)
 {
         int errors = 0;
         IOR_offset_t transferCount = 0;
diff --git a/src/mdtest.c b/src/mdtest.c
index b81b143..3e102de 100644
--- a/src/mdtest.c
+++ b/src/mdtest.c
@@ -346,7 +346,7 @@ static void remove_file (const char *path, uint64_t itemNum) {
 
 static void create_file (const char *path, uint64_t itemNum) {
     char curr_item[MAX_PATHLEN];
-    void *aiori_fh = NULL;
+    aiori_fd_t *aiori_fh = NULL;
 
     if ( (itemNum % ITEM_COUNT==0 && (itemNum != 0))) {
         VERBOSE(3,5,"create file: "LLU"", itemNum);
@@ -443,7 +443,7 @@ void collective_helper(const int dirs, const int create, const char* path, uint6
         VERBOSE(3,5,"create file: %s", curr_item);
 
         if (create) {
-            void *aiori_fh;
+            aiori_fd_t *aiori_fh;
 
             //create files
             aiori_fh = backend->create (curr_item, IOR_WRONLY | IOR_CREAT, backend_options);
@@ -622,7 +622,7 @@ void mdtest_stat(const int random, const int dirs, const long dir_iter, const ch
 void mdtest_read(int random, int dirs, const long dir_iter, char *path) {
     uint64_t parent_dir, item_num = 0;
     char item[MAX_PATHLEN], temp[MAX_PATHLEN];
-    void *aiori_fh;
+    aiori_fd_t *aiori_fh;
 
     VERBOSE(1,-1,"Entering mdtest_read on %s", path );