diff --git a/configure.in b/configure.in
index edb8ad6e..55d14e67 100644
--- a/configure.in
+++ b/configure.in
@@ -55,14 +55,19 @@ pid = waitpid (-1, &status, 0);
 ],
 		 AC_DEFINE(HAVE_UNION_WAIT))
 
-AC_COMPILE_CHECK(sys_siglist declaration in signal.h,
-		 [#include <signal.h>], [char *msg = *(sys_siglist + 1);],
+AC_COMPILE_CHECK(sys_siglist declaration in signal.h or unistd.h,
+		 [#include <signal.h>
+/* NetBSD declares sys_siglist in <unistd.h>.  */
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif], [char *msg = *(sys_siglist + 1);],
 		 AC_DEFINE(SYS_SIGLIST_DECLARED))
 
 # The presence of the following is not meant to imply
 # that make necessarily works on those systems.
 AC_DYNIX_SEQ
 AC_XENIX_DIR
+AC_IRIX_SUN
 
 AC_SUBST(REMOTE) REMOTE=stub
 AC_WITH(customs, [REMOTE=cstms