diff --git a/thd_iin.c b/thd_iin.c
index 49db1b5..4a030fc 100644
--- a/thd_iin.c
+++ b/thd_iin.c
@@ -21,16 +21,20 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#if defined (__MACH__)
+#define USE_NAMED_SEMAPHORES
+#endif
+
 #if defined (_BUILD_WIN32)
 #  include <windows.h>
 #  include "sema.h" /* POSIX semaphores for win32 */
 #else
 #  include <pthread.h>
-#if defined (__MACH__)
-#  include <dispatch/dispatch.h>
-#else
 #  include <semaphore.h>
 #endif
+#if defined (USE_NAMED_SEMAPHORES)
+#include <unistd.h>
+#include <limits.h>
 #endif
 #include <stdio.h>
 #include <string.h>
@@ -67,8 +71,8 @@ typedef struct threaded_decorator_type
   job_t job;
 
   /* both are exclusive => at any moment only one is acquirable */
-#if defined (__MACH__)
-  dispatch_semaphore_t worker_lock, master_lock;
+#ifdef USE_NAMED_SEMAPHORES
+  sem_t *worker_lock, *master_lock;
 #else
   sem_t worker_lock, master_lock;
 #endif
@@ -93,8 +97,8 @@ thd_loop (void *p)
 
   do
     {
-#if defined(__MACH__)
-      int result = dispatch_semaphore_wait (thd->worker_lock, DISPATCH_TIME_FOREVER);
+#if defined(USE_NAMED_SEMAPHORES)
+      int result = sem_wait (thd->worker_lock);
 #else
       int result = sem_wait (&thd->worker_lock);
 #endif
@@ -116,8 +120,8 @@ thd_loop (void *p)
 	  dest->num_sectors = job->num_sectors;
 
 	  /* unlock master */
-#if defined(__MACH__)
-    dispatch_semaphore_signal (thd->master_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+    sem_post (thd->master_lock);
 #else
 	  sem_post (&thd->master_lock);
 #endif
@@ -126,8 +130,8 @@ thd_loop (void *p)
   while (!thd->done);
 
   /* notify master */
-#if defined(__MACH__)
-  dispatch_semaphore_signal (thd->master_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+  sem_post (thd->master_lock);
 #else
   sem_post (&thd->master_lock);
 #endif
@@ -148,8 +152,8 @@ thd_read (iin_t *iin,
 
   do
     {
-#if defined(__MACH__)
-      result = dispatch_semaphore_wait (thd->master_lock, DISPATCH_TIME_FOREVER);
+#if defined(USE_NAMED_SEMAPHORES)
+      result = sem_wait (thd->master_lock);
 #else
       result = sem_wait (&thd->master_lock);
 #endif
@@ -169,8 +173,8 @@ thd_read (iin_t *iin,
 	      thd->job.start_sector = start_sector;
 	      thd->job.num_sectors = num_sectors;
 	      thd->job.dest = thd->buf + (thd->active_buf % 2);
-#if defined(__MACH__)
-        dispatch_semaphore_signal (thd->worker_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+        sem_post (thd->worker_lock);
 #else
 	      sem_post (&thd->worker_lock);
 #endif
@@ -186,8 +190,8 @@ thd_read (iin_t *iin,
       thd->job.start_sector = start_sector + num_sectors;
       thd->job.num_sectors = IIN_NUM_SECTORS;
       thd->job.dest = thd->buf + (++thd->active_buf % 2);
-#if defined(__MACH__)
-        dispatch_semaphore_signal (thd->worker_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+        sem_post (thd->worker_lock);
 #else
         sem_post (&thd->worker_lock);
 #endif
@@ -195,8 +199,8 @@ thd_read (iin_t *iin,
   else
     /* since there is no pre-fetch scheduled,
        unlock master or the next read call would block forever */
-#if defined(__MACH__)
-    dispatch_semaphore_signal (thd->master_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+    sem_post (thd->master_lock);
 #else
     sem_post (&thd->master_lock);
 #endif
@@ -226,24 +230,24 @@ thd_close (iin_t *iin)
   int result;
 
   /* wait for worker to finish... */
-#if defined(__MACH__)
-  dispatch_semaphore_wait (thd->master_lock, DISPATCH_TIME_FOREVER);
+#if defined(USE_NAMED_SEMAPHORES)
+  sem_wait (thd->master_lock);
 #else
   sem_wait (&thd->master_lock);
 #endif
   thd->done = 1;
-#if defined(__MACH__)
-  dispatch_semaphore_signal (thd->worker_lock);
-  dispatch_semaphore_wait (thd->master_lock, DISPATCH_TIME_FOREVER);
+#if defined(USE_NAMED_SEMAPHORES)
+  sem_post (thd->worker_lock);
+  sem_wait (thd->master_lock);
 #else
   sem_post (&thd->worker_lock);
   sem_wait (&thd->master_lock);
 #endif
 
   /* clean-up */
-#if defined(__MACH__)
-  dispatch_release (thd->worker_lock);
-  dispatch_release (thd->master_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+  sem_close (thd->worker_lock);
+  sem_close (thd->master_lock);
 #else
   sem_destroy (&thd->worker_lock);
   sem_destroy (&thd->master_lock);
@@ -281,6 +285,9 @@ thd_create (iin_t *worker)
 {
   u_int32_t total_sectors, sector_size;
   threaded_decorator_t *thd;
+#if defined(USE_NAMED_SEMAPHORES)
+  char sema_name_buf[NAME_MAX - 4];
+#endif
 
   if (worker->stat (worker, &sector_size, &total_sectors) != RET_OK)
     return (NULL);
@@ -303,20 +310,26 @@ thd_create (iin_t *worker)
       thd->done = 0;
 
       /* master is unlocked, worker is locked; would run on 1st need */
-#if defined(__MACH__)
-      thd->worker_lock = dispatch_semaphore_create(0);
+#if defined(USE_NAMED_SEMAPHORES)
+      snprintf (sema_name_buf, sizeof(sema_name_buf), "hdl_dump%x_%i", getpid (), 0);
+      thd->worker_lock = sem_open ((const char *)sema_name_buf, O_CREAT);
       if (thd->worker_lock != NULL)
 #else
       if (sem_init (&thd->worker_lock, 0, 0) == 0)
 #endif
 	{
-#if defined(__MACH__)
-    thd->master_lock = dispatch_semaphore_create(1);
+#if defined(USE_NAMED_SEMAPHORES)
+    sem_unlink ((const char *)sema_name_buf);
+    snprintf (sema_name_buf, sizeof(sema_name_buf), "hdl_dump%x_%i", getpid (), 1);
+    thd->master_lock = sem_open ((const char *)sema_name_buf, O_CREAT);
     if (thd->master_lock != NULL)
 #else
 	  if (sem_init (&thd->master_lock, 0, 1) == 0)
 #endif
 	    {
+#if defined(USE_NAMED_SEMAPHORES)
+        sem_unlink ((const char *)sema_name_buf);
+#endif
 #if defined (_BUILD_WIN32)
 	      DWORD thread_id = 0;
 	      HANDLE h = CreateThread (NULL, 0, &thd_loop, thd, 0, &thread_id);
@@ -329,14 +342,14 @@ thd_create (iin_t *worker)
 		return ((iin_t*) thd); /* unix: success */
 #endif
 
-#if defined(__MACH__)
-        dispatch_release (thd->master_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+        (void) sem_close (thd->master_lock);
 #else
 	      (void) sem_destroy (&thd->master_lock);
 #endif
 	    }
-#if defined(__MACH__)
-    dispatch_release (thd->worker_lock);
+#if defined(USE_NAMED_SEMAPHORES)
+    (void) sem_close (thd->worker_lock);
 #else
 	  (void) sem_destroy (&thd->worker_lock);
 #endif