diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 4080d236403..f873bfa33d1 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,7 @@
+2000-10-18  Chip Salzenberg  <chip@valinux.com>
+
+        * libio/libio.h (_IO_USER_LOCK): Define.
+
 2000-10-18   Benjamin Kosnik  <bkoz@purist.soma.redhat.com>
 
 	* libsupc++/Makefile.am (exception): Change exception.cc to
diff --git a/libstdc++-v3/libio/libio.h b/libstdc++-v3/libio/libio.h
index d26a5e59798..e662f489187 100644
--- a/libstdc++-v3/libio/libio.h
+++ b/libstdc++-v3/libio/libio.h
@@ -133,6 +133,7 @@
 #define _IO_IS_APPENDING 0x1000
 #define _IO_IS_FILEBUF 0x2000
 #define _IO_BAD_SEEN 0x4000
+#define _IO_USER_LOCK 0x8000
 
 /* These are "formatting flags" matching the iostream fmtflags enum values. */
 #define _IO_SKIPWS 01