diff --git a/library/io/duplex-stream.factor b/library/io/duplex-stream.factor
index 80fbd07c77..fa6a463c2a 100644
--- a/library/io/duplex-stream.factor
+++ b/library/io/duplex-stream.factor
@@ -61,10 +61,9 @@ M: duplex-stream stream-close
     #! buffer needs to be flushed before we close the fd.
     dup duplex-stream-closed? [
         t over set-duplex-stream-closed?
-        dup
-        duplex-stream-out stream-close
-        duplex-stream-in stream-close
-    ] unless ;
+        dup duplex-stream-out stream-close
+        dup duplex-stream-in stream-close
+    ] unless drop ;
 
 M: duplex-stream set-timeout
     2dup