diff --git a/configure b/configure
index cb8001c..aae7494 100755
--- a/configure
+++ b/configure
@@ -23782,6 +23782,91 @@
 LIBS_SAVE=$LIBS
 LIBS="$LIBS $LIBM"
 
+# For multiprocessing module, check that sem_open
+# actually works.  For FreeBSD versions <= 7.2,
+# the kernel module that provides POSIX semaphores
+# isn't loaded by default, so an attempt to call
+# sem_open results in a 'Signal 12' error.
+{ echo "$as_me:$LINENO: checking whether POSIX semaphores are enabled" >&5
+echo $ECHO_N "checking whether POSIX semaphores are enabled... $ECHO_C" >&6; }
+if test "${ac_cv_posix_semaphores_enabled+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test "$cross_compiling" = yes; then
+  ac_cv_posix_semaphores_enabled=yes
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <semaphore.h>
+#include <sys/stat.h>
+
+int main(void) {
+  sem_t *a = sem_open("/autoconf", O_CREAT, S_IRUSR|S_IWUSR, 0);
+  if (a == SEM_FAILED) {
+    perror("sem_open");
+    return 1;
+  }
+  sem_close(a);
+  return 0;
+}
+
+_ACEOF
+rm -f conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_posix_semaphores_enabled=yes
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+( exit $ac_status )
+ac_cv_posix_semaphores_enabled=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+
+
+
+fi
+
+{ echo "$as_me:$LINENO: result: $ac_cv_posix_semaphores_enabled" >&5
+echo "${ECHO_T}$ac_cv_posix_semaphores_enabled" >&6; }
+if test $ac_cv_posix_semaphores_enabled = no
+then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_BROKEN_POSIX_SEMAPHORES 1
+_ACEOF
+
+fi
+
+
 # Multiprocessing check for broken sem_getvalue
 { echo "$as_me:$LINENO: checking for broken sem_getvalue" >&5
 echo $ECHO_N "checking for broken sem_getvalue... $ECHO_C" >&6; }