diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index cdcb4d1eadf..1751a3d6638 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2007-11-30  Tom Tromey  <tromey@redhat.com>
+
+	PR preprocessor/32868:
+	* gcc.dg/cpp/pr32868.c: New file.
+
 2007-11-30  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR fortran/34248
diff --git a/gcc/testsuite/gcc.dg/cpp/pr32868.c b/gcc/testsuite/gcc.dg/cpp/pr32868.c
new file mode 100644
index 00000000000..ea896214c30
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr32868.c
@@ -0,0 +1,6 @@
+/* PR preprocessor/32868.  It is ok to redefine __STDC_FORMAT_MACROS.  */
+
+/* { dg-do preprocess } */
+
+#define __STDC_FORMAT_MACROS 1
+#define __STDC_FORMAT_MACROS 1
diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index bac5e860389..3701c8000a6 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,9 @@
+2007-11-30  Tom Tromey  <tromey@redhat.com>
+
+	PR preprocessor/32868:
+	* macro.c (_cpp_create_definition): Special case
+	__STDC_FORMAT_MACROS.
+
 2007-11-16  Michael Matz  <matz@suse.de>
 
 	* files.c (search_path_head): Fix check for absolute paths.
diff --git a/libcpp/macro.c b/libcpp/macro.c
index f3a4420ae40..754e2f77b90 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -1695,7 +1695,8 @@ _cpp_create_definition (cpp_reader *pfile, cpp_hashnode *node)
   /* Enter definition in hash table.  */
   node->type = NT_MACRO;
   node->value.macro = macro;
-  if (! ustrncmp (NODE_NAME (node), DSC ("__STDC_")))
+  if (! ustrncmp (NODE_NAME (node), DSC ("__STDC_"))
+      && ustrcmp (NODE_NAME (node), (const uchar *) "__STDC_FORMAT_MACROS"))
     node->flags |= NODE_WARN;
 
   return ok;