diff --git a/bootstrap.conf b/bootstrap.conf
index 5f15a82f9..6119c0f88 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -213,6 +213,7 @@ gnulib_modules="
   physmem
   pipe-posix
   pipe2
+  pipe2-safer
   posix-shell
   posix_spawn
   posix_spawn_file_actions_addclose
diff --git a/cfg.mk b/cfg.mk
index 27b63f93b..aa2c86e23 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -603,6 +603,19 @@ sc_require_stdlib_safer:
 	else :;								\
 	fi
 
+# Ensure that "unistd--.h" is used where appropriate.
+sc_require_unistd_safer:
+	@if $(VC_LIST_EXCEPT) | grep -l '\.[ch]$$' > /dev/null; then	\
+	  files=$$(grep -El '$(begword)(pipe2?|dup[23]?) ?\('		\
+		   $$($(VC_LIST_EXCEPT)					\
+	      | grep '\.[ch]$$'));					\
+	  test -n "$$files" && grep -LE 'include "unistd--.h"' $$files	\
+	      | grep . &&						\
+	  { echo '$(ME): the above files should use "unistd--.h"'	\
+		1>&2; exit 1; } || :;					\
+	else :;								\
+	fi
+
 sc_prohibit_perl_hash_quotes:
 	@prohibit="\{'[A-Z_]+' *[=}]"					\
 	halt="in Perl code, write \$$hash{KEY}, not \$$hash{'K''EY'}"	\
diff --git a/gl/lib/fd-reopen.c b/gl/lib/fd-reopen.c
index 10fb40bbd..607235feb 100644
--- a/gl/lib/fd-reopen.c
+++ b/gl/lib/fd-reopen.c
@@ -23,7 +23,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
-#include <unistd.h>
+#include "unistd--.h"
 
 /* Open a file to a particular file descriptor.  This is like standard
    'open', except it always returns DESIRED_FD if successful.  */
diff --git a/src/sort.c b/src/sort.c
index c35890ec2..e20ed2c8f 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -51,6 +51,7 @@
 #include "stdlib--.h"
 #include "strnumcmp.h"
 #include "term-sig.h"
+#include "unistd--.h"
 #include "xmemcoll.h"
 #include "xnanosleep.h"
 #include "xstrtol.h"
diff --git a/src/split.c b/src/split.c
index e5fd0ae2e..4786df827 100644
--- a/src/split.c
+++ b/src/split.c
@@ -40,6 +40,7 @@
 #include "sig2str.h"
 #include "sys-limits.h"
 #include "temp-stream.h"
+#include "unistd--.h"
 #include "xbinary-io.h"
 #include "xdectoint.h"
 #include "xstrtol.h"
diff --git a/src/yes.c b/src/yes.c
index 91e540eba..1a1d74ce5 100644
--- a/src/yes.c
+++ b/src/yes.c
@@ -27,6 +27,7 @@
 #include "full-write.h"
 #include "isapipe.h"
 #include "long-options.h"
+#include "unistd--.h"
 
 /* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "yes"