diff --git a/kwant/physics/leads.py b/kwant/physics/leads.py
index d058a6008c307923d7657658a74bdf459ff02e92..f2ac1a8ebc3f20a96e7aa4b043a24a3067c8a222 100644
--- a/kwant/physics/leads.py
+++ b/kwant/physics/leads.py
@@ -46,6 +46,7 @@ if bdiag_broken:  # skip coverage
         return b_mat
 
 
+# TODO: Remove the workaround once we depend on scipy >= 1.0
 def lstsq(a, b):
     """Least squares version that works also with 0-shaped matrices."""
     if a.shape[1] == 0: