Index: b/configure.ac
===================================================================
--- b/configure.ac
+++ b/configure.ac
@@ -294,6 +294,64 @@
                 ])
 LIBS=$gl_saved_libs
 
+      AC_MSG_CHECKING([whether the sem_init created accessable semapore for child process])
+      AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <errno.h>
+#include <semaphore.h>
+#include <sys/wait.h>
+static sem_t sceptre_buffer;
+static sem_t *sceptre = &sceptre_buffer;
+int main() 
+{
+int res;
+  // create semaphore
+  if(sem_init (sceptre, 0, 1)<0) {
+     return 1;
+  }
+  do {
+    // unlock
+    res = sem_wait (sceptre);
+  } while (res < 0 && errno == EINTR);
+  if(res) {
+    return 1;
+  }
+  pid_t pid;
+  pid = fork ();
+  if (pid == (pid_t)-1)
+    {
+      return 1;
+    }
+  else if (pid)
+   {
+     int status;
+     waitpid(-1,&status,0);
+     if(status) {
+       return 1;
+     }
+   } else {
+      // lock in child
+     if(sem_post (sceptre) != 0)
+       {
+        return 1;
+       }
+     return 0;
+   }
+  return 0;
+}]])],
+   [have_working_sem_init=yes],
+   [have_working_sem_init=no],
+   [
+changequote(,)dnl
+         case "$host_os" in
+           aix* ) have_working_sem_init=no ;;
+           *)     have_working_sem_init=yes ;;
+         esac
+changequote([,])dnl
+   ])
+      AC_MSG_RESULT($have_working_sem_init)
+if test x"$have_working_sem_init" = xno ; then
+   AC_DEFINE(HAVE_BROKEN_SEM_INIT,1,[Define if sem_init can not create accessable semapore for child process.])
+fi
+
 
 #
 # Set NETLIBS
Index: b/src/npth.c
===================================================================
--- b/src/npth.c
+++ b/src/npth.c
@@ -181,6 +181,7 @@
      sem_init.  */
   errno = 0;
 
+#ifndef HAVE_BROKEN_SEM_INIT
   /* The semaphore is not shared and binary.  */
   res = sem_init (sceptre, 0, 1);
   if (res < 0)
@@ -204,6 +205,10 @@
 #endif
         }
     }
+#else
+  if (try_sem_open (&sceptre))
+     return errno;
+#endif
 
   LEAVE();
   return 0;
Index: b/tests/Makefile.am
===================================================================
--- b/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -28,7 +28,7 @@
 
 ## Process this file with automake to produce Makefile.in
 
-TESTS = t-mutex t-thread
+TESTS = t-mutex t-thread t-fork
 
 # We explicitly require POSIX.1-2001 so that pthread_rwlock_t is
 # available when build with c99.
Index: b/tests/t-fork.c
===================================================================
--- /dev/null
+++ b/tests/t-fork.c
@@ -0,0 +1,49 @@
+/* t-mutex.c
+ * Copyright 2011, 2012 g10 Code GmbH
+ *
+ * This file is free software; as a special exception the author gives
+ * unlimited permission to copy and/or distribute it, with or without
+ * modifications, as long as this notice is preserved.
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+ * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include "t-support.h"
+
+
+int
+main (int argc, char *argv[])
+{
+  int rc;
+
+  rc = npth_init ();
+  fail_if_err (rc);
+  npth_unprotect ();
+  npth_protect ();
+  pid_t pid;
+  npth_sigev_init ();
+  npth_sigev_add (SIGHUP);
+  npth_sigev_fini ();
+  pid = fork ();
+  if (pid == (pid_t)-1)
+    {
+      fail_msg ("fork failed");
+      exit (1);
+    }
+  else if (pid)
+   {
+     int status;
+     info_msg("forked"); 
+     waitpid(-1,&status,0);
+     if(status) {
+       exit(1);
+     }
+   } else { 
+     npth_unprotect ();
+     info_msg("child exit"); 
+     exit(0); 
+   }
+  return 0;
+}