diff --git a/c/src/ChangeLog b/c/src/ChangeLog
index 5a03c6a706..9864e49a74 100644
--- a/c/src/ChangeLog
+++ b/c/src/ChangeLog
@@ -1,3 +1,7 @@
+2008-08-18	Ralf Corsepius <ralf.corsepius@rtems.org>
+
+	* aclocal/prog-cc.m4: Add -Wnested-externs.
+
 2008-08-18	Ralf Corsépius <ralf.corsepius@rtems.org>
 
 	* libchip/network/dec21140.c: Add missing prototype.
diff --git a/c/src/aclocal/prog-cc.m4 b/c/src/aclocal/prog-cc.m4
index 19d758e40b..4371c17c6c 100644
--- a/c/src/aclocal/prog-cc.m4
+++ b/c/src/aclocal/prog-cc.m4
@@ -38,7 +38,7 @@ AC_SUBST(GCCSPECS)
 AS_IF([test "$GCC" = yes],[
 RTEMS_CFLAGS="$RTEMS_CFLAGS -Wall"
 # FIXME: This should be removed in production releases
-RTEMS_CFLAGS="$RTEMS_CFLAGS -Wimplicit-function-declaration -Wstrict-prototypes"
+RTEMS_CFLAGS="$RTEMS_CFLAGS -Wimplicit-function-declaration -Wstrict-prototypes -Wnested-externs"
 m4_if([$1],,[],[RTEMS_CFLAGS="$RTEMS_CFLAGS $1"])
 ])
 AC_SUBST(RTEMS_CFLAGS)