diff --git a/include/light/bounce.hh b/include/light/bounce.hh
index 938d76c3..72a391ee 100644
--- a/include/light/bounce.hh
+++ b/include/light/bounce.hh
@@ -31,6 +31,7 @@
 
 typedef struct {
     std::vector<glm::vec3> poly;
+    std::vector<glm::vec4> poly_edgeplanes;
     glm::vec3 pos;
     std::map<int, glm::vec3> colorByStyle;
     glm::vec3 componentwiseMaxColor; // cached maximum color in the colorByStyle, used for culling so we don't need to loop through colorByStyle
diff --git a/light/bounce.cc b/light/bounce.cc
index 29d26f44..e0be8506 100644
--- a/light/bounce.cc
+++ b/light/bounce.cc
@@ -231,6 +231,7 @@ AddBounceLight(const vec3_t pos, const std::map<int, glm::vec3> &colorByStyle, c
     
     bouncelight_t l;
     l.poly = GLM_FacePoints(bsp, face);
+    l.poly_edgeplanes = GLM_MakeInwardFacingEdgePlanes(l.poly);
     l.pos = vec3_t_to_glm(pos);
     l.colorByStyle = colorByStyle;