diff --git a/src/calibre/utils/ipc/worker.py b/src/calibre/utils/ipc/worker.py
index 0c1e251cd4..ebc4246128 100644
--- a/src/calibre/utils/ipc/worker.py
+++ b/src/calibre/utils/ipc/worker.py
@@ -196,8 +196,14 @@ def main():
 
         notifier.queue.put(None)
 
-    sys.stdout.flush()
-    sys.stderr.flush()
+    try:
+        sys.stdout.flush()
+    except EnvironmentError:
+        pass  # Happens sometimes on OS X for GUI processes (EPIPE)
+    try:
+        sys.stderr.flush()
+    except EnvironmentError:
+        pass  # Happens sometimes on OS X for GUI processes (EPIPE)
     return 0