diff --git a/mrdna/readers/segmentmodel_from_cadnano.py b/mrdna/readers/segmentmodel_from_cadnano.py
index 2936c4d86a6321b8df9c61c69fa5bf5a2ec62868..763362010935dbdcafb5e7a7c0ab773046c994cb 100644
--- a/mrdna/readers/segmentmodel_from_cadnano.py
+++ b/mrdna/readers/segmentmodel_from_cadnano.py
@@ -105,6 +105,7 @@ def get_helix_angle(part, helix_id, indices, index_offset=0, fwd=True):
     twist_per_base = tpr*360./bpr
         # angle = eulerZ - twist_per_base*indices + 0.5*mgroove + 180
     angle = eulerZ - twist_per_base*indices - 0.5*mgroove
+    angle=angle*(np.pi/180)
     cos,sin = (np.cos(angle), np.sin(angle))
     R = np.zeros( (len(angle),3,3) )
     R[:,0,0] = cos