diff --git a/Framework/PythonInterface/plugins/algorithms/SaveHKLCW.py b/Framework/PythonInterface/plugins/algorithms/SaveHKLCW.py
index 94e8edb4b9e0b491879faf886cfdf3077ada7b1e..62453bc4be8fece65043bf208eb7045519510dfe 100644
--- a/Framework/PythonInterface/plugins/algorithms/SaveHKLCW.py
+++ b/Framework/PythonInterface/plugins/algorithms/SaveHKLCW.py
@@ -80,7 +80,7 @@ class SaveHKLCW(PythonAlgorithm):
                     R = p.getGoniometerMatrix()
                     RU = np.dot(R, U)
                     ki = ki_n * (2 * np.pi / p.getWavelength())
-                    kf_n = ki + p.getQLabFrame()  # direction of scattered wavevector
+                    kf_n = ki - p.getQLabFrame()  # direction of scattered wavevector
                     kf_n = kf_n * (1. / kf_n.norm())
                     dir_cos_1 = np.dot(RU.T, -ki_n)  # notice ki direction is reversed
                     dir_cos_2 = np.dot(RU.T, kf_n)