diff --git a/src/OpenFOAM/primitives/quaternion/quaternionI.H b/src/OpenFOAM/primitives/quaternion/quaternionI.H
index e692707c30..3c550b8de7 100644
--- a/src/OpenFOAM/primitives/quaternion/quaternionI.H
+++ b/src/OpenFOAM/primitives/quaternion/quaternionI.H
@@ -259,7 +259,7 @@ inline Foam::quaternion::quaternion
               - rotationTensor.zz()
             );
 
-            w_ = (rotationTensor.xz() - rotationTensor.xz())/s;
+            w_ = (rotationTensor.xz() - rotationTensor.zx())/s;
             v_[0] = (rotationTensor.xy() + rotationTensor.yx())/s;
             v_[1] = 0.25*s;
             v_[2] = (rotationTensor.yz() + rotationTensor.zy())/s;