diff --git a/bilby/gw/detector/networks.py b/bilby/gw/detector/networks.py
index 00a8e14cfe545c94d2ab67c2781afe452ba65acb..20b1f54b5fc94bb10d3db4ce051b70237234d4be 100644
--- a/bilby/gw/detector/networks.py
+++ b/bilby/gw/detector/networks.py
@@ -273,7 +273,7 @@ class InterferometerList(list):
     """
 
     def to_pickle(self, outdir="outdir", label="ifo_list"):
-        utils.check_directory_exists_and_if_not_mkdir("outdir")
+        utils.check_directory_exists_and_if_not_mkdir(outdir)
         label = label + "_" + "".join(ifo.name for ifo in self)
         filename = self._filename_from_outdir_label_extension(
             outdir, label, extension="pkl"