diff --git a/mne/channels/layout.py b/mne/channels/layout.py
index 043bb9c33b7..7b9acc33df9 100644
--- a/mne/channels/layout.py
+++ b/mne/channels/layout.py
@@ -65,7 +65,7 @@ def __init__(self, box, pos, names, ids, kind):
         self.ids = ids
         self.kind = kind
 
-    def save(self, fname, overwrite=False):
+    def save(self, fname, *, overwrite=False):
         """Save Layout to disk.
 
         Parameters
@@ -89,7 +89,7 @@ def save(self, fname, overwrite=False):
         elif fname.suffix == ".lay":
             out_str = ""
         else:
-            raise ValueError("Unknown layout type. Should be of type " ".lout or .lay.")
+            raise ValueError("Unknown layout type. Should be of type .lout or .lay.")
 
         for ii in range(x.shape[0]):
             out_str += "%03d %8.2f %8.2f %8.2f %8.2f %s\n" % (