diff --git a/src/Base/ViewProj.cpp b/src/Base/ViewProj.cpp
index 36383df116..b8d5096508 100644
--- a/src/Base/ViewProj.cpp
+++ b/src/Base/ViewProj.cpp
@@ -54,6 +54,17 @@ ViewProjMatrix::~ViewProjMatrix()
 {
 }
 
+Matrix4D ViewProjMatrix::getProjectionMatrix (void) const
+{
+    // Return the same matrix as passed to the constructor
+    Matrix4D mat(_clMtx);
+    if (isOrthographic) {
+        mat.move(-0.5, -0.5, -0.5);
+        mat.scale(2.0, 2.0, 2.0);
+    }
+    return mat;
+}
+
 template<typename Vec>
 void perspectiveTransform(const Base::Matrix4D& mat, Vec& pnt)
 {
diff --git a/src/Base/ViewProj.h b/src/Base/ViewProj.h
index 7a31c2429f..306c2f6ece 100644
--- a/src/Base/ViewProj.h
+++ b/src/Base/ViewProj.h
@@ -68,7 +68,7 @@ public:
     Vector3f inverse (const Vector3f &rclPt) const;
     Vector3d inverse (const Vector3d &rclPt) const;
 
-    Matrix4D getProjectionMatrix (void) const { return _clMtx; }
+    Matrix4D getProjectionMatrix (void) const;
 
 protected:
     bool isOrthographic;