diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index db383b145c0..adb0fa381f7 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2000-07-21  H.J. Lu  (hjl@gnu.org)
+
+	        * acinclude.m4: Include <features.h> for glibc testing.
+	        * aclocal.m4: Likewise.
+
+	        * configure: Rebuild.
+	
 2000-07-20  H.J. Lu  (hjl@gnu.org)
 
         * acinclude.m4: Change "#pragma system_header" to
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index d9839ec61ef..28bdef72207 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -1186,6 +1186,7 @@ AC_DEFUN(GLIBCPP_ENABLE_CSTDIO, [
           *-*-linux*)
   	    AC_MSG_CHECKING([for glibc version >= 2.2])
   	    AC_EGREP_CPP([ok], [
+	    #include <features.h>
   	    #if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) 
     		ok
   	    #endif
@@ -1514,7 +1515,7 @@ dnl Then, if any (well almost any) other make is called, and GNU make also
 dnl exists, then the other make wraps the GNU make.
 dnl
 dnl @author John Darrington <j.darrington@elvis.murdoch.edu.au>
-dnl @version $Id: acinclude.m4,v 1.43 2000/07/19 00:57:37 bkoz Exp $
+dnl @version $Id: acinclude.m4,v 1.44 2000/07/21 01:02:31 bkoz Exp $
 dnl
 dnl #### Changes for libstdc++-v3:  reformatting and linewrapping; prepending
 dnl #### GLIBCPP_ to the macro name; adding the :-make fallback in the
diff --git a/libstdc++-v3/aclocal.m4 b/libstdc++-v3/aclocal.m4
index d65ade9d60a..a80bbe90f6c 100644
--- a/libstdc++-v3/aclocal.m4
+++ b/libstdc++-v3/aclocal.m4
@@ -1198,6 +1198,7 @@ AC_DEFUN(GLIBCPP_ENABLE_CSTDIO, [
           *-*-linux*)
   	    AC_MSG_CHECKING([for glibc version >= 2.2])
   	    AC_EGREP_CPP([ok], [
+	    #include <features.h>
   	    #if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) 
     		ok
   	    #endif
@@ -1526,7 +1527,7 @@ dnl Then, if any (well almost any) other make is called, and GNU make also
 dnl exists, then the other make wraps the GNU make.
 dnl
 dnl @author John Darrington <j.darrington@elvis.murdoch.edu.au>
-dnl @version $Id: acinclude.m4,v 1.43 2000/07/19 00:57:37 bkoz Exp $
+dnl @version $Id: aclocal.m4,v 1.45 2000/07/21 01:02:31 bkoz Exp $
 dnl
 dnl #### Changes for libstdc++-v3:  reformatting and linewrapping; prepending
 dnl #### GLIBCPP_ to the macro name; adding the :-make fallback in the