diff --git a/libmproxy/dump.py b/libmproxy/dump.py
index 0eba363ad..5781764c2 100644
--- a/libmproxy/dump.py
+++ b/libmproxy/dump.py
@@ -217,7 +217,7 @@ class DumpMaster(flow.FlowMaster):
 # begin nocover
     def shutdown(self):
         if self.o.wfile:
-            self.wfile.fo.close()
+            self.fwriter.fo.close()
         return flow.FlowMaster.shutdown(self)
 
     def run(self):