diff --git a/panda/src/collide/collisionPlane.cxx b/panda/src/collide/collisionPlane.cxx
index aca3b15f59..367024a577 100644
--- a/panda/src/collide/collisionPlane.cxx
+++ b/panda/src/collide/collisionPlane.cxx
@@ -207,7 +207,7 @@ fill_viz_geom() {
   LVector3f p1, p2, p3, p4;
 
   LVector3f normal = get_normal();
-  float D = _plane._d;
+  float D = _plane[3];
 
   if (fabs(normal[0]) > fabs(normal[1]) &&
       fabs(normal[0]) > fabs(normal[2])) {
diff --git a/panda/src/collide/collisionPolygon.cxx b/panda/src/collide/collisionPolygon.cxx
index fb8a20a6b9..f613cab1ea 100644
--- a/panda/src/collide/collisionPolygon.cxx
+++ b/panda/src/collide/collisionPolygon.cxx
@@ -945,7 +945,7 @@ to_3d(const LVecBase2f &point2d) const {
   nassertr(!point2d.is_nan(), LPoint3f(0.0f, 0.0f, 0.0f));
 
   LVector3f normal = get_normal();
-  float D = get_plane()._d;
+  float D = get_plane()[3];
 
   nassertr(!normal.is_nan(), LPoint3f(0.0f, 0.0f, 0.0f));
   nassertr(!cnan(D), LPoint3f(0.0f, 0.0f, 0.0f));