diff --git a/artiq/frontend/artiq_flash.py b/artiq/frontend/artiq_flash.py
index c6aea8fb7..9e360ec87 100755
--- a/artiq/frontend/artiq_flash.py
+++ b/artiq/frontend/artiq_flash.py
@@ -129,6 +129,7 @@ def main():
         ])
     finally:
         if conv:
+            os.close(bin_handle)
             os.unlink(bin)