diff --git a/libio/ChangeLog b/libio/ChangeLog
index d3a5eff74e0..384d4ef05ed 100644
--- a/libio/ChangeLog
+++ b/libio/ChangeLog
@@ -1,3 +1,7 @@
+Sun Sep 28 12:04:21 1997  Jason Merrill  <jason@yorick.cygnus.com>
+
+	* libio.h: Don't use _IO_LOCK_T if it's not defined.
+
 Fri Sep 26 20:56:41 1997  Ulrich Drepper  <drepper@rtl.cygnus.com>
 
 	Based on a patch by H.J. Lu  (hjl@gnu.ai.mit.edu).
diff --git a/libio/libio.h b/libio/libio.h
index d5e20f53bbe..3d7bce3c181 100644
--- a/libio/libio.h
+++ b/libio/libio.h
@@ -226,7 +226,9 @@ struct _IO_FILE {
 
   /*  char* _save_gptr;  char* _save_egptr; */
 
+#ifdef _IO_LOCK_T
   _IO_LOCK_T _lock;
+#endif
 };
 
 #ifndef __cplusplus