diff --git a/GraphicsView/include/CGAL/Qt/quaternion_impl.h b/GraphicsView/include/CGAL/Qt/quaternion_impl.h
index 5dd599da5d6..616ef35137f 100644
--- a/GraphicsView/include/CGAL/Qt/quaternion_impl.h
+++ b/GraphicsView/include/CGAL/Qt/quaternion_impl.h
@@ -529,11 +529,6 @@ Quaternion Quaternion::squadTangent(const Quaternion &before,
   return e;
 }
 
-CGAL_INLINE_FUNCTION
-std::ostream &operator<<(std::ostream &o, const Quaternion &Q) {
-  return o << Q[0] << '\t' << Q[1] << '\t' << Q[2] << '\t' << Q[3];
-}
-
 /*! Returns a random unit Quaternion.
 
 You can create a randomly directed unit vector using:
@@ -556,4 +551,10 @@ Quaternion Quaternion::randomQuaternion() {
   qreal t2 = 2.0 * CGAL_PI * (rand() / (qreal)RAND_MAX);
   return Quaternion(sin(t1) * r1, cos(t1) * r1, sin(t2) * r2, cos(t2) * r2);
 }
-}}
+  
+}} // namespace CGAL::qglviewer
+
+CGAL_INLINE_FUNCTION
+std::ostream &operator<<(std::ostream &o, const CGAL::qglviewer::Quaternion &Q) {
+  return o << Q[0] << '\t' << Q[1] << '\t' << Q[2] << '\t' << Q[3];
+}
diff --git a/GraphicsView/include/CGAL/Qt/vec_impl.h b/GraphicsView/include/CGAL/Qt/vec_impl.h
index 340c6cbf62c..b7b317f3031 100644
--- a/GraphicsView/include/CGAL/Qt/vec_impl.h
+++ b/GraphicsView/include/CGAL/Qt/vec_impl.h
@@ -174,8 +174,9 @@ void Vec::initFromDOMElement(const QDomElement &element) {
   *this = v;
 }
 
+}} // namespace CGAL::qglviewer
+
 CGAL_INLINE_FUNCTION
-std::ostream &operator<<(std::ostream &o, const Vec &v) {
+std::ostream &operator<<(std::ostream &o, const CGAL::qglviewer::Vec &v) {
   return o << v.x << '\t' << v.y << '\t' << v.z;
 }
-}}