diff --git a/m4/fclose.m4 b/m4/fclose.m4
index 6bd1ad8..e939d30 100644
--- a/m4/fclose.m4
+++ b/m4/fclose.m4
@@ -1,4 +1,4 @@
-# fclose.m4 serial 6
+# fclose.m4 serial 7
 dnl Copyright (C) 2008-2015 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,6 +7,7 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_FCLOSE],
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST])
 
   gl_FUNC_FFLUSH_STDIN
   if test $gl_cv_func_fflush_stdin != yes; then
@@ -17,4 +18,8 @@ AC_DEFUN([gl_FUNC_FCLOSE],
   if test $REPLACE_CLOSE = 1; then
     REPLACE_FCLOSE=1
   fi
+
+  case "$host_os" in
+    openedition) REPLACE_FCLOSE=1 ;;
+  esac
 ])
diff --git a/m4/strstr.m4 b/m4/strstr.m4
index 040c0b9..e3e528d 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -1,4 +1,4 @@
-# strstr.m4 serial 16
+# strstr.m4 serial 17
 dnl Copyright (C) 2008-2015 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -67,6 +67,12 @@ AC_DEFUN([gl_FUNC_STRSTR],
     AC_CACHE_CHECK([whether strstr works in linear time],
       [gl_cv_func_strstr_linear],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#ifdef __MVS__
+/* z/OS does not deliver signals while strstr() is running (thanks to
+   restrictions on its LE runtime), which prevents us from limiting the
+   running time of this test.  */
+# error "This test does not work properly on z/OS"
+#endif
 #include <signal.h> /* for signal */
 #include <string.h> /* for strstr */
 #include <stdlib.h> /* for malloc */
diff --git a/m4/wchar_h.m4 b/m4/wchar_h.m4
index 9d1b0f8..c926c4b 100644
--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@@ -7,7 +7,7 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl Written by Eric Blake.
 
-# wchar_h.m4 serial 39
+# wchar_h.m4 serial 40
 
 AC_DEFUN([gl_WCHAR_H],
 [
@@ -81,8 +81,14 @@ AC_DEFUN([gl_WCHAR_H_INLINE_OK],
 extern int zero (void);
 int main () { return zero(); }
 ]])])
+     dnl Do not rename the object file from conftest.$ac_objext to
+     dnl conftest1.$ac_objext, as this will cause the link to fail on
+     dnl z/OS when using the XPLINK object format (due to duplicate
+     dnl CSECT names). Instead, temporarily redefine $ac_compile so
+     dnl that the object file has the latter name from the start.
+     save_ac_compile="$ac_compile"
+     ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest1/`
      if AC_TRY_EVAL([ac_compile]); then
-       mv conftest.$ac_objext conftest1.$ac_objext
        AC_LANG_CONFTEST([
          AC_LANG_SOURCE([[#define wcstod renamed_wcstod
 /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
@@ -95,8 +101,9 @@ int main () { return zero(); }
 #include <wchar.h>
 int zero (void) { return 0; }
 ]])])
+       dnl See note above about renaming object files.
+       ac_compile=`echo "$save_ac_compile" | sed s/conftest/conftest2/`
        if AC_TRY_EVAL([ac_compile]); then
-         mv conftest.$ac_objext conftest2.$ac_objext
          if $CC -o conftest$ac_exeext $CFLAGS $LDFLAGS conftest1.$ac_objext conftest2.$ac_objext $LIBS >&AS_MESSAGE_LOG_FD 2>&1; then
            :
          else
@@ -104,6 +111,7 @@ int zero (void) { return 0; }
          fi
        fi
      fi
+     ac_compile="$save_ac_compile"
      rm -f conftest1.$ac_objext conftest2.$ac_objext conftest$ac_exeext
     ])
   if test $gl_cv_header_wchar_h_correct_inline = no; then