diff --git a/mrdna/segmentmodel.py b/mrdna/segmentmodel.py
index a08670e324f1a3c8fc59c472da56deed41d64d21..5dd33f5b6dd75a942162f161d9b2bde8d4c7901f 100644
--- a/mrdna/segmentmodel.py
+++ b/mrdna/segmentmodel.py
@@ -2423,7 +2423,7 @@ class SegmentModel(ArbdModel):
                     parent = self._getParent( b1, b2 )
 
                     """ Add heuristic 90 degree potential to keep orientation bead orthogonal """
-                    k = 0.5*k_dsdna_angle(sep)
+                    k = 0.25*k_dsdna_angle(sep)
                     pot = self.get_angle_potential(k,90)
                     parent.add_angle(o1,b1,b2, pot)
                     parent.add_angle(b1,b2,o2, pot)