diff --git a/mrdna/arbdmodel/coords.py b/mrdna/arbdmodel/coords.py
index da1957322715cf0debe8e535f27b6829bbd06175..41e75dea11e52d5216a8d4bed6ade3836550837d 100644
--- a/mrdna/arbdmodel/coords.py
+++ b/mrdna/arbdmodel/coords.py
@@ -110,6 +110,7 @@ def quaternion_to_matrix(q):
     return np.array(R)
 
 def quaternion_from_matrix( R ):
+    R = R.T
     q = np.empty(4)
     if R[2,2] < 0:
         if R[0,0] > R[1,1]: