Index: /trunk/ccl/level-1/l1-sysio.lisp
===================================================================
--- /trunk/ccl/level-1/l1-sysio.lisp	(revision 5994)
+++ /trunk/ccl/level-1/l1-sysio.lisp	(revision 5995)
@@ -639,5 +639,6 @@
 	    (unix-rename (namestring actual-filename) (probe-file-x filename)))
 	  (delete-file actual-filename)))
-      (setq *open-file-streams* (nremove s *open-file-streams*)))))
+      (with-lock-grabbed (*open-file-streams-lock*)
+        (setq *open-file-streams* (nremove s *open-file-streams*))))))
 
 
@@ -842,5 +843,6 @@
                   (if (eq direction :probe)
                     (close fstream)
-                    (push fstream *open-file-streams*))
+                    (with-lock-grabbed (*open-file-streams-lock*)
+                      (push fstream *open-file-streams*)))
                   fstream)))))))))