diff --git a/gwcelery/tasks/external_skymaps.py b/gwcelery/tasks/external_skymaps.py
index dbe41ebd52f5bb06a0074fd1cf680fe07bf8cf89..86cbac57c71ba668c5fcb91e8fe341c580eb72db 100644
--- a/gwcelery/tasks/external_skymaps.py
+++ b/gwcelery/tasks/external_skymaps.py
@@ -90,11 +90,12 @@ def _download_skymaps(se_filename, ext_filename, se_id, ext_id):
 
 
 @app.task(shared=False)
-def combine_skymaps(skymap1filebytes, skymap2filebytes):
+def combine_skymaps(skymapfilesbytes):
     """This task combines the two input skymaps, in this case the external
     trigger skymap and the LVC skymap and writes to a temporary output file. It
     then returns the contents of the file as a byte array.
     """
+    skymap1filebytes, skymap2filebytes = skymapbytes
     with NamedTemporaryFile(mode='rb', suffix='.fits.gz') as combinedskymap, \
             NamedTemporaryFile(content=skymap1filebytes) as skymap1file, \
             NamedTemporaryFile(content=skymap2filebytes) as skymap2file, \