diff --git a/src/configure.in b/src/configure.in
index 159d1525fe0de50f069cfa4cd17987c3b440aa59..241eab80d951ef229b11a55c06259bf018284cc0 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -1,4 +1,4 @@
-AC_REVISION("$Id: configure.in,v 1.183 1998/05/15 18:46:12 grubba Exp $")
+AC_REVISION("$Id: configure.in,v 1.184 1998/05/17 20:37:12 grubba Exp $")
 AC_INIT(interpret.c)
 AC_CONFIG_HEADER(machine.h)
 
@@ -1445,6 +1445,23 @@ fi
 
 #############################################################################
 
+AC_MSG_CHECKING([for union wait (old BSD convention)])
+AC_CACHE_VAL(pike_cv_union_wait, [ AC_TRY_COMPILE([
+#ifdef HAVE_SYS_WAIT_H
+#include <sys/wait.h>
+], [
+  union wait status;
+  exit(0);
+], pike_cv_union_wait=yes, pike_cv_union_wait=no)
+])
+
+AC_MSG_RESULT($pike_cv_union_wait)
+if test "x$pike_cv_union_wait" = "xyes" ; then
+  AC_DEFINE(HAVE_UNION_WAIT)
+fi
+
+#############################################################################
+
 AC_MSG_CHECKING(how to extract an unsigned char)
 AC_CACHE_VAL(pike_cv_method_extract_uchar,
 [