diff --git a/python/len_spec/__init__.py b/python/len_spec/__init__.py
index 6fded93a..f90bd011 100644
--- a/python/len_spec/__init__.py
+++ b/python/len_spec/__init__.py
@@ -96,6 +96,10 @@ def length_spectrum(manifold, bits_prec : Optional[int] = None, verified : bool
         if not tile.word:
             continue
 
+        if r13_dot(tile.o13_matrix * mcomplex.R13_baseTetInCenter,
+                   mcomplex.R13_baseTetInCenter) > -(mcomplex.baseTetInRadius/2).cosh():
+            continue
+
         num += 1
 
         r = tile.lower_bound_cover_radius