diff --git a/interface/src/devices/DdeFaceTracker.cpp b/interface/src/devices/DdeFaceTracker.cpp
index ca2f5bd48e..30165624af 100644
--- a/interface/src/devices/DdeFaceTracker.cpp
+++ b/interface/src/devices/DdeFaceTracker.cpp
@@ -388,7 +388,7 @@ void DdeFaceTracker::decodePacket(const QByteArray& buffer) {
         // Compute relative rotation
         rotation = glm::inverse(_referenceRotation) * rotation;
         if (isFiltering) {
-            glm::quat r = rotation * glm::inverse(_headRotation);
+            glm::quat r = glm::normalize(rotation * glm::inverse(_headRotation));
             float theta = 2 * acos(r.w);
             glm::vec3 angularVelocity;
             if (theta > EPSILON) {
diff --git a/interface/src/devices/Faceshift.cpp b/interface/src/devices/Faceshift.cpp
index 409f359afa..b517f9d67b 100644
--- a/interface/src/devices/Faceshift.cpp
+++ b/interface/src/devices/Faceshift.cpp
@@ -213,7 +213,7 @@ void Faceshift::receive(const QByteArray& buffer) {
                     glm::quat newRotation = glm::quat(data.m_headRotation.w, -data.m_headRotation.x,
                                                       data.m_headRotation.y, -data.m_headRotation.z);
                     // Compute angular velocity of the head
-                    glm::quat r = newRotation * glm::inverse(_headRotation);
+                    glm::quat r = glm::normalize(newRotation * glm::inverse(_headRotation));
                     float theta = 2 * acos(r.w);
                     if (theta > EPSILON) {
                         float rMag = glm::length(glm::vec3(r.x, r.y, r.z));